00:01
In a cone not drawn to scale.
00:03
Edge ab has a length of 26 centimeters.
00:07
The height is 16 centimeters.
00:11
In the slant is in the so edge ab has a length of 26 centimeters.
00:24
The diagonal is of ac has a length of 42 centimeters.
00:31
The radius r of the cone is 12 centimeters and the height is 16 centimeters and the slant is 20 centimeters.
00:39
Give your answers to each of the following to two significant figures.
00:43
Find the surface area of the cone.
00:46
So to find the surface area of a cone, surface, just looking up the surface area of a cone formula.
01:02
So to find the surface area of a cone, i'm going to do pi times the radius times the slant plus pi times the radius squared.
01:12
So i'm going to do 3 .14 times 12 times 20 plus 3 .14 times 12 squared.
01:28
So surface area equals 3 .14 times 12 times 20 is 753 .6 plus 3 .14 times 14 times 14 .4 times 14 .4 .53 .6 plus because 12 squared is 144, so 452 .16.
01:54
So then surface area equals, so plus 753 .6, is 1 ,205 .76.
02:06
So 1 ,205 .76 centimeters squared.
02:13
Find the volume of the cone.
02:15
So the volume, i'm going to do pi times the radius squared.
02:19
Times the height divided by 3.
02:21
So 3 .14 times the radius of 12 squared times the height of 16 divided by 3.
02:30
So 3 .14 times 144 times 16 is 7 ,234 .56...