# I don't know how to solve this?

##### 1 Answer

May 2, 2018

a.

b.

#### Explanation:

You can look at the problem this way:

The question is basically asking you that what other value of

You can recall from the symmetry of the unit circle that the following results always hold:

This is because sine is always positive in the first and the second quadrant while cosine is always positive in the first and the fourth quadrant. Hence, we can solve the given problem:

so

so

Hope this helps!