00:01
We're being asked to find all the values of theta that will make this equation true.
00:04
Well, to do this, i'm going to factor out a cosine theta from both terms.
00:08
So i will be left with cosine theta times the quantity of two cosine theta plus one.
00:14
And it's all equal to zero.
00:16
So now i'm going to set both factors equal to zero.
00:18
Well, the cosine of theta could be equal to zero or two cosine of theta plus one could equal to zero.
00:27
So let's solve both of these equations.
00:28
Well, when is the cosine of theta equal to zero? well, this happens at 90 degrees as well as 270 degrees.
00:37
Now, our directions didn't specify whether to use degrees or radiance, so you could use either one.
00:43
Now, i'm going to solve the second equation.
00:45
To do that, i'm going to subtract one from both sides, so we'll have two cosine of theta is equal to negative 1.
00:51
Then we'll divide both sides by 2, so we'll have the cosine of theta is equal to negative 1 1�...