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Algebra and Trigonometry

James Stewart, Lothar Redlin, Saleem Watson

Chapter 5

Trigonometric Functions: Right Triangle Approach - all with Video Answers

Educators


Section 1

Angle Measure

01:51

Problem 1

(a) The radian measure of an angle $\theta$ is the length of the ______ that subtends the angle in a circle of radius _______ .
(b) To convert degrees to radians, we multiply by ______ .
(c) To convert radians to degrees, we multiply by ______ .

Martha Richards
Martha Richards
Numerade Educator
00:52

Problem 2

A central angle $\theta$ is drawn in a circle of radius $r,$ as in the figure below.
(a) The length of the arc subtended by $\theta$ is $s=$ ______ .
(b) The area of the sector with central angle $\theta$ $A=$ _______ .

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
02:03

Problem 3

Suppose a point moves along a circle with radius $r$ as shown in the figure below. The point travels a distance $s$ along the circle in time $t.$
(a) The angular speed of the point is $\omega=$ ______ .
(b) The linear speed of the point is $v=$ ______ .
(c) The linear speed $v$ and the angular speed $\omega$ are related by the equation $v=$ ______ .

Prashant Bana
Prashant Bana
Numerade Educator
01:21

Problem 4

Object $A$ is traveling along a circle of radius $2,$ and Object $B$ is traveling along a circle of radius $5 .$ The objects have the same angular speed. Do the objects have the same linear speed? If not, which object has the greater linear speed?

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:50

Problem 5

From Degrees to Radians Find the radian measure of the angle with the given degree measure. Round your answer to three decimal places.
$15^{\circ}$

Martha Richards
Martha Richards
Numerade Educator
00:50

Problem 6

From Degrees to Radians Find the radian measure of the angle with the given degree measure. Round your answer to three decimal places.
$36^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:57

Problem 7

From Degrees to Radians Find the radian measure of the angle with the given degree measure. Round your answer to three decimal places.
$54^{\circ}$

Martha Richards
Martha Richards
Numerade Educator
00:51

Problem 8

From Degrees to Radians Find the radian measure of the angle with the given degree measure. Round your answer to three decimal places.
$75^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
01:26

Problem 9

From Degrees to Radians Find the radian measure of the angle with the given degree measure. Round your answer to three decimal places.
$-45^{\circ}$

Martha Richards
Martha Richards
Numerade Educator
00:42

Problem 10

From Degrees to Radians Find the radian measure of the angle with the given degree measure. Round your answer to three decimal places.
$-30^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:53

Problem 11

From Degrees to Radians Find the radian measure of the angle with the given degree measure. Round your answer to three decimal places.
$100^{\circ}$

Martha Richards
Martha Richards
Numerade Educator
00:38

Problem 12

From Degrees to Radians Find the radian measure of the angle with the given degree measure. Round your answer to three decimal places.
$200^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:44

Problem 13

From Degrees to Radians Find the radian measure of the angle with the given degree measure. Round your answer to three decimal places.
$1000^{\circ}$

Martha Richards
Martha Richards
Numerade Educator
00:33

Problem 14

From Degrees to Radians Find the radian measure of the angle with the given degree measure. Round your answer to three decimal places.
$3600^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:43

Problem 15

From Degrees to Radians Find the radian measure of the angle with the given degree measure. Round your answer to three decimal places.
$-70^{\circ}$

Martha Richards
Martha Richards
Numerade Educator
00:38

Problem 16

From Degrees to Radians Find the radian measure of the angle with the given degree measure. Round your answer to three decimal places.
$-150^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:35

Problem 17

From Radians to Degrees Find the degree measure of the angle with the given radian measure.
$\frac{5 \pi}{3}$

Martha Richards
Martha Richards
Numerade Educator
00:28

Problem 18

From Radians to Degrees Find the degree measure of the angle with the given radian measure.
$\frac{3 \pi}{4}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:38

Problem 19

From Radians to Degrees Find the degree measure of the angle with the given radian measure.
$\frac{5 \pi}{6}$

Martha Richards
Martha Richards
Numerade Educator
00:31

Problem 20

From Radians to Degrees Find the degree measure of the angle with the given radian measure.
$-\frac{3 \pi}{2}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:46

Problem 21

From Radians to Degrees Find the degree measure of the angle with the given radian measure.
3

Martha Richards
Martha Richards
Numerade Educator
01:09

Problem 22

From Radians to Degrees Find the degree measure of the angle with the given radian measure.
$-2$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:47

Problem 23

From Radians to Degrees Find the degree measure of the angle with the given radian measure.
$-1.2$

Martha Richards
Martha Richards
Numerade Educator
01:12

Problem 24

From Radians to Degrees Find the degree measure of the angle with the given radian measure.
3.4

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:31

Problem 25

From Radians to Degrees Find the degree measure of the angle with the given radian measure.
$\frac{\pi}{10}$

Martha Richards
Martha Richards
Numerade Educator
00:36

Problem 26

From Radians to Degrees Find the degree measure of the angle with the given radian measure.
$\frac{5 \pi}{18}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:45

Problem 27

From Radians to Degrees Find the degree measure of the angle with the given radian measure.
$-\frac{2 \pi}{15}$

Martha Richards
Martha Richards
Numerade Educator
00:41

Problem 28

From Radians to Degrees Find the degree measure of the angle with the given radian measure.
$-\frac{13 \pi}{12}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
01:48

Problem 29

Coterminal Angles The measure of an angle in standard position is given. Find two positive angles and two negative angles that are coterminal with the given angle.
$50^{\circ}$

Martha Richards
Martha Richards
Numerade Educator
01:56

Problem 30

Coterminal Angles The measure of an angle in standard position is given. Find two positive angles and two negative angles that are coterminal with the given angle.
$135^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
02:01

Problem 31

Coterminal Angles The measure of an angle in standard position is given. Find two positive angles and two negative angles that are coterminal with the given angle.
$\frac{3 \pi}{4}$

Martha Richards
Martha Richards
Numerade Educator
02:33

Problem 32

Coterminal Angles The measure of an angle in standard position is given. Find two positive angles and two negative angles that are coterminal with the given angle.
$\frac{11 \pi}{6}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
01:34

Problem 33

Coterminal Angles The measure of an angle in standard position is given. Find two positive angles and two negative angles that are coterminal with the given angle.
$-\frac{\pi}{4}$

Martha Richards
Martha Richards
Numerade Educator
01:48

Problem 34

Coterminal Angles The measure of an angle in standard position is given. Find two positive angles and two negative angles that are coterminal with the given angle.
$-45^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:45

Problem 35

Coterminal Angles? The measures of two angles in standard position are given. Determine whether the angles are coterminal.
$70^{\circ}, 430^{\circ}$

Martha Richards
Martha Richards
Numerade Educator
01:18

Problem 36

Coterminal Angles? The measures of two angles in standard position are given. Determine whether the angles are coterminal.
$-30^{\circ}, 330^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:52

Problem 37

Coterminal Angles? The measures of two angles in standard position are given. Determine whether the angles are coterminal.
$\frac{5 \pi}{6}, \frac{17 \pi}{6}$

Martha Richards
Martha Richards
Numerade Educator
02:16

Problem 38

Coterminal Angles? The measures of two angles in standard position are given. Determine whether the angles are coterminal.
$\frac{32 \pi}{3}, \frac{11 \pi}{3}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:55

Problem 39

Coterminal Angles? The measures of two angles in standard position are given. Determine whether the angles are coterminal.
$155^{\circ}, \quad 875^{\circ}$

Martha Richards
Martha Richards
Numerade Educator
00:58

Problem 40

Coterminal Angles? The measures of two angles in standard position are given. Determine whether the angles are coterminal.
$50^{\circ}, 340^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:43

Problem 41

Finding a Coterminal Angle Find an angle between $0^{\circ}$ and $360^{\circ}$ that is coterminal with the given angle.
$400^{\circ}$

Martha Richards
Martha Richards
Numerade Educator
00:53

Problem 42

Finding a Coterminal Angle Find an angle between $0^{\circ}$ and $360^{\circ}$ that is coterminal with the given angle.
$375^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
01:11

Problem 43

Finding a Coterminal Angle Find an angle between $0^{\circ}$ and $360^{\circ}$ that is coterminal with the given angle.
$780^{\circ}$

Martha Richards
Martha Richards
Numerade Educator
View

Problem 44

Finding a Coterminal Angle Find an angle between $0^{\circ}$ and $360^{\circ}$ that is coterminal with the given angle.
$-100^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
01:37

Problem 45

Finding a Coterminal Angle Find an angle between $0^{\circ}$ and $360^{\circ}$ that is coterminal with the given angle.
$-800^{\circ}$

Martha Richards
Martha Richards
Numerade Educator
01:12

Problem 46

Finding a Coterminal Angle Find an angle between $0^{\circ}$ and $360^{\circ}$ that is coterminal with the given angle.
$1270^{\circ}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
04:00

Problem 47

Finding a Coterminal Angle Find an angle between 0 and 2$\pi$ that is coterminal with the given angle.
$\frac{19 \pi}{6}$

KS
Karuna Sangam
Numerade Educator
01:00

Problem 48

Finding a Coterminal Angle Find an angle between 0 and 2$\pi$ that is coterminal with the given angle.
$-\frac{5 \pi}{3}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
03:54

Problem 49

Finding a Coterminal Angle Find an angle between 0 and 2$\pi$ that is coterminal with the given angle.
25$\pi$

Christian Capanelli
Christian Capanelli
Numerade Educator
00:44

Problem 50

Finding a Coterminal Angle Find an angle between 0 and 2$\pi$ that is coterminal with the given angle.
10

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
06:35

Problem 51

Finding a Coterminal Angle Find an angle between 0 and 2$\pi$ that is coterminal with the given angle.
$\frac{17 \pi}{4}$

Zulfiqar Ali
Zulfiqar Ali
Numerade Educator
01:33

Problem 52

Finding a Coterminal Angle Find an angle between 0 and 2$\pi$ that is coterminal with the given angle.
$\frac{51 \pi}{2}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
01:03

Problem 53

Circular Arcs Find the length $s$ of the circular arc, the radius $r$ of the circle, or the central angle $\theta,$ as indicated.

Martha Richards
Martha Richards
Numerade Educator
02:48

Problem 54

Circular Arcs Find the length $s$ of the circular arc, the radius $r$ of the circle, or the central angle $\theta,$ as indicated.

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:35

Problem 55

Circular Arcs Find the length $s$ of the circular arc, the radius $r$ of the circle, or the central angle $\theta,$ as indicated.

Martha Richards
Martha Richards
Numerade Educator
01:15

Problem 56

Circular Arcs Find the length $s$ of the circular arc, the radius $r$ of the circle, or the central angle $\theta,$ as indicated.

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:40

Problem 57

Circular Arcs Find the length $s$ of the circular arc, radius $r$ of the circle, or the central angle $\theta,$ as indicated.
Find the length $s$ of the arc that subtends a central angle of measure 3 rad in a circle of radius 5 $\mathrm{cm} .$

Martha Richards
Martha Richards
Numerade Educator
01:15

Problem 58

Circular Arcs Find the length $s$ of the circular arc, radius $r$ of the circle, or the central angle $\theta,$ as indicated.
Find the length $s$ of the arc that subtends a central angle of measure $40^{\circ}$ in a circle of radius 12 $\mathrm{m} .$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:54

Problem 59

Circular Arcs Find the length $s$ of the circular arc, radius $r$ of the circle, or the central angle $\theta,$ as indicated.
A central angle $\theta$ in a circle of radius 9 $\mathrm{m}$ is subtended by an arc of length 14 $\mathrm{m} .$ Find the measure of $\theta$ in degrees and radians.

Martha Richards
Martha Richards
Numerade Educator
01:50

Problem 60

Circular Arcs Find the length $s$ of the circular arc, radius $r$ of the circle, or the central angle $\theta,$ as indicated.
An arc of length 15 ft subtends a central angle $\theta$ in a circle of radius 9 ft. Find the measure of $\theta$ in degrees and radians.

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
01:06

Problem 61

Circular Arcs Find the length $s$ of the circular arc, radius $r$ of the circle, or the central angle $\theta,$ as indicated.
Find the radius $r$ of the circle if an arc of length 15 $\mathrm{m}$ on the circle subtends a central angle of 5$\pi / 6 .$

Martha Richards
Martha Richards
Numerade Educator
01:45

Problem 62

Circular Arcs Find the length $s$ of the circular arc, radius $r$ of the circle, or the central angle $\theta,$ as indicated.
Find the radius $r$ of the circle if an arc of length 20 $\mathrm{cm}$ on the circle subtends a central angle of $50^{\circ} .$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
02:02

Problem 63

Area of a Circular Sector These exercises involve the formula for the area of a circular sector.
Find the area of the sector shown in each figure.

Martha Richards
Martha Richards
Numerade Educator
03:06

Problem 64

Area of a Circular Sector These exercises involve the formula for the area of a circular sector.
Find the radius of each circle if the area of the sector

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:57

Problem 65

Area of a Circular Sector These exercises involve the formula for the area of a circular sector.
Find the area of a sector with central angle 2$\pi / 3$ rad in a circle of radius 10 $\mathrm{m} .$

Martha Richards
Martha Richards
Numerade Educator
01:19

Problem 66

Area of a Circular Sector These exercises involve the formula for the area of a circular sector.
A sector of a circle has a central angle of $145^{\circ} .$ Find the area of the sector if the radius of the circle is 6 $\mathrm{ft}$ .

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
02:14

Problem 67

Area of a Circular Sector These exercises involve the formula for the area of a circular sector.
The area of a sector of a circle with a central angle of $140^{\circ}$ is 70 $\mathrm{m}^{2} .$ Find the radius of the circle.

Martha Richards
Martha Richards
Numerade Educator
01:44

Problem 68

Area of a Circular Sector These exercises involve the formula for the area of a circular sector.
The area of a sector of a circle with a central angle of 5$\pi / 12$ rad is 20 $\mathrm{m}^{2} .$ Find the radius of the circle.

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
01:10

Problem 69

Area of a Circular Sector These exercises involve the formula for the area of a circular sector.
A sector of a circle of radius 80 $\mathrm{mi}$ has an area of 1600 $\mathrm{mi}^{2} .$ Find the central angle (in radians) of the sector.

Martha Richards
Martha Richards
Numerade Educator
03:01

Problem 70

Area of a Circular Sector These exercises involve the formula for the area of a circular sector.
The area of a circle is 600 $\mathrm{m}^{2} .$ Find the area of a sector of this circle that subtends a central angle of 3 $\mathrm{rad} .$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
02:32

Problem 71

Area of a Sector of a Circle Three circles with radii $1,2,$ and 3 $\mathrm{ft}$ are externally tangent to one another, as shown in the figure. Find the area of the sector of the circle of radius 1 that is cut off by the line segments joining the center of that circle to the centers of the other two circles.

Joseph Lentino
Joseph Lentino
Numerade Educator
02:48

Problem 72

Comparing a Triangle and a Sector of a Circle Two wood sticks and a metal rod, each of length $1,$ are connected to form a triangle with angle $\theta_{1}$ at the point $P$ , as shown in the first figure below. The rod is then bent to form an arc of a circle with center $P$ , resulting in a smaller angle $\theta_{2}$ at the point $P$ as shown in the second figure. Find $\theta_{1}, \theta_{2},$ and $\theta_{1}-\theta_{2}$

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
03:41

Problem 73

Clocks and Angles $\operatorname{In} 1 \mathrm{h}$ the minute hand on a clock moves through a complete circle, and the hour hand moves through $\frac{1}{12}$ of a circle.
Through how many radians do the minute hand and the hour hand move between $1 : 00$ P.M. and $1 : 45$ P.M. (on the same day)?

Emily Burns
Emily Burns
Numerade Educator
02:08

Problem 74

Clocks and Angles $\operatorname{In} 1 \mathrm{h}$ the minute hand on a clock moves through a complete circle, and the hour hand moves through $\frac{1}{12}$ of a circle.
Through how many radians do the minute hand and the hour hand move between $1 : 00 \mathrm{P.M.}$ and $6 : 45 \mathrm{P.M.}$ (on the same day)?

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
02:01

Problem 75

Travel Distance A car's wheels are 28 in. in diameter. How far (in mi.) will the car travel if its wheels revolve 10,000 times without slipping?

Emily Burns
Emily Burns
Numerade Educator
02:06

Problem 76

Wheel Revolutions How many revolutions will a car wheel of diameter 30 in. make as the car travels a distance of one mile?

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
05:38

Problem 77

Latitudes Pittsburgh, Pennsylvania, and Miami, Florida, lie approximately on the same meridian. Pittsburgh has a latitude of $40.5^{\circ} \mathrm{N},$ and Miami has a latitude of $25.5^{\circ} \mathrm{N}$ . Find the distance between these two cities. (The radius of the earth is 3960 $\mathrm{mi.}$.)

Arulmozhi T
Arulmozhi T
Numerade Educator
02:03

Problem 78

Latitudes Memphis, Tennessee, and New Orleans, Louisiana, lie approximately on the same meridian. Memphis has a latitude of $35^{\circ} \mathrm{N}$ , and New Orleans has a latitude of $30^{\circ} \mathrm{N} .$ Find the distance between these two cities. (The radius of the earth is 3960 $\mathrm{mi.}$)

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:24

Problem 79

Orbit of the Earth Find the distance that the earth travels in one day in its path around the sun. Assume that a year has 365 days and that the path of the earth around the sun is a circle of radius 93 million miles. [Note: The path of the earth around the sun is actually an ellipse with the sun at one focus (see Section 12.2$) .$ This ellipse, however, has very small eccentricity, so it is nearly circular.]

YS
Yuankun Song
Numerade Educator
02:46

Problem 80

Circumference of the Earth The Greek mathematician Eratosthenes (ca. 276-195 B.C.) measured the circumference of the earth from the following observations. He noticed that on a certain day the sun shone directly down a deep well in Syene (modern Aswan). At the same time in Alexandria, 500 miles north (on the same meridian), the rays of the sun shone at an angle of $7.2^{\circ}$ to the zenith. Use this information and the figure to find the radius and circumference of the earth.

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
01:46

Problem 81

Nautical Miles Find the distance along an arc on the surface of the earth that subtends a central angle of 1 minute (1 minute $=\frac{1}{60}$ degree). This distance is called a nautical mile. (The radius of the earth is 3960 $\mathrm{mi.}$)

AR
Aakash Ramachandran
Numerade Educator
01:21

Problem 82

Irrigation An irrigation system uses a straight sprinkler pipe 300 ft long that pivots around a central point as shown. Because of an obstacle the pipe is allowed to pivot through $280^{\circ}$ only. Find the area irrigated by this system.

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
03:46

Problem 83

Windshield Wipers The top and bottom ends of a windshield wiper blade are 34 in. and 14 in., respectively, from the pivot point. While in operation, the wiper sweeps through $135^{\circ} .$ Find the area swept by the blade.

Suman Saurav Thakur
Suman Saurav Thakur
Numerade Educator
03:35

Problem 84

The Tethered Cow A cow is tethered by a 100 -ft rope to the inside corner of an L-shaped building, as shown in the figure. Find the area that the cow can graze.

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
02:33

Problem 85

Fan A ceiling fan with 16 -in. blades rotates at 45 $\mathrm{rpm}$ .
(a) Find the angular speed of the fan in rad/min.
(b) Find the linear speed of the tips of the blades in in./min.

Emily Burns
Emily Burns
Numerade Educator
02:54

Problem 86

Radial Saw A radial saw has a blade with a 6 -in. radius. Suppose that the blade spins at 1000 $\mathrm{rpm.}$
(a) Find the angular speed of the blade in rad/min.
(b) Find the linear speed of the sawteeth in ft/s.

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
03:00

Problem 87

Winch A winch of radius 2 $\mathrm{ft}$ is used to lift heavy loads. If the winch makes 8 revolutions every $15 \mathrm{s},$ find the speed at which the load is rising.

Emily Burns
Emily Burns
Numerade Educator
02:27

Problem 88

Speed of a Car The wheels of a car have radius 11 in. and are rotating at 600 $\mathrm{rpm} .$ Find the speed of the car in mi/h.

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
02:51

Problem 89

Speed at the Equator The earth rotates about its axis once every 23 h 56 min $4 \mathrm{s},$ and the radius of the earth is 3960 $\mathrm{mi}$ . Find the linear speed of a point on the equator in mi/h.

Emily Burns
Emily Burns
Numerade Educator
03:07

Problem 90

Truck Wheels A truck with 48 -in.-diameter wheels is traveling at 50 $\mathrm{mi} / \mathrm{h}$.
(a) Find the angular speed of the wheels in rad/min.
(b) How many revolutions per minute do the wheels make?

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
01:33

Problem 91

Speed of a Current To measure the speed of a current, scientists place a paddle wheel in the stream and observe the rate at which it rotates. If the paddle wheel has radius 0.20 $\mathrm{m}$ and rotates at $100 \mathrm{rpm},$ find the speed of the current in $\mathrm{m} / \mathrm{s}$.

Emily Burns
Emily Burns
Numerade Educator
02:58

Problem 92

Bicycle Wheel The sprockets and chain of a bicycle are shown in the figure. The pedal sprocket has a radius of 4 in. the wheel sprocket a radius of 2 in.. and the wheel a radius of 13 in. The cyclist pedals at 40 rpm.
(a) Find the angular speed of the wheel sprocket.
(b) Find the speed of the bicycle. (Assume that the wheel turns at the same rate as the wheel sprocket.)

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
05:23

Problem 93

Conical Cup A conical cup is made from a circular piece of paper with radius 6 $\mathrm{cm}$ by cutting out a sector and joining the edges as shown below. Suppose $\theta=5 \pi / 3 .$
(a) Find the circumference $C$ of the opening of the cup.
(b) Find the radius $r$ of the opening of the cup. $[$Hint: Use $C=2 \pi r . ]$
(c) Find the height $h$ of the cup. [Hint : Use the Pythagorean Theorem.]
(d) Find the volume of the cup.

Suman Saurav Thakur
Suman Saurav Thakur
Numerade Educator
01:35

Problem 94

Conical Cup In this exercise we find the volume of the conical cup in Exercise 93 for any angle $\theta$.
(a) Follow the steps in Exercise 93 to show that the volume of the cup as a function of $\theta$ is
$$V(\theta)=\frac{9}{\pi^{2}} \theta^{2} \sqrt{4 \pi^{2}-\theta^{2}}, \quad 0<\theta<2 \pi$$
(b) Graph the function $V$ .
(c) For what angle $\theta$ is the volume of the cup a maximum?

Anthony Pisaturo
Anthony Pisaturo
Numerade Educator
00:44

Problem 95

WRITE: Different Ways of Measuring Angles The custom of measuring angles using degrees, with $360^{\circ}$ in a circle, dates back to the ancient Babylonians, who used a number system based on groups of $60 .$ Another system of measuring angles divides the circle into 400 units, called grads. In this system a right angle is 100 grad, so this fits in with our base 10 number system.
Write a short essay comparing the advantages and disadvantages of these two systems and the radian system of measuring angles. Which system do you prefer? Why?

Katelyn Chen
Katelyn Chen
Numerade Educator