00:01
So for 1a, we can simply take both terms and set them equal to 0 in order to find the values of theta that make the equation equals 0 or the statement to be true.
00:19
So set this equal to 0 first, add 9 to both sides, and we get sine squared of theta is equal to 9.
00:29
Theta here doesn't have a solution because if you take the square root of both sides, it would be sine of theta is equal to 3, and since 3 is greater than 1, there is no solution.
00:43
However, on the other side, if you move one to the other side and divide by 2 from both sides, we get that the cosine of theta is equal to 1⁄2, and that's a pretty simple trigonometric relationship.
01:00
So, theta will be equal to pi over 3.
01:06
And since that's the only solution of the two, this is the only solution.
01:13
So 1b states that sine of theta is equal to, or 1 over the sign of theta is equal to negative 5.
01:20
If you take the reciprocal of both sides, we get that sine of theta is equal to negative 1 over 5.
01:28
There's nothing you can do but plug this into a calculator.
01:31
Theta is equal to the arc sine of negative 1 over 5.
01:33
Theta is equal to 3 .34.
01:36
So for 1c, we get that the tangent of theta is equal to negative 10.
01:41
Again, we can't do anything but plug in.
01:43
Theta is equal to the arc tangent or the inverse tangent of negative 10.
01:48
And once you do that, theta is equal to 1 .67.
01:52
So for 2a, we get that sine of theta is equal to negative 0 .45.
01:57
Again, we can't do anything but plug this into a calculator.
02:00
Theta is equal to the arc sign of negative 0 .45.
02:04
That is equal to 3 .61.
02:07
So for 2b, we have a long expanded polynomial of trigonometric expressions.
02:19
If you factor out cosine of theta, which i already did here, you get this expression right here.
02:26
And again, this is two terms multiplied together to equal to zero, so we can set both equal to zero and then solve for theta.
02:32
So sine of theta is equal to four.
02:34
That has no solution because 4 is greater than 1.
02:36
Cosine of theta is equal to 0...