### Home > CCA2 > Chapter 8 > Lesson 8.1.1 > Problem8-16

8-16.

Without a calculator, find two solutions $0°\leθ<360°$ that make each of the following equations true.

1. $\cosθ=\frac{1}{2}$

Draw a unit circle.

The cosine is where the $x-$value (red line) is $\frac{1}{2}.$

1. $\tan θ = −1$
$135° \text{and}\ 315°$
1. $\sinθ=\frac{\sqrt{3}}{2}$
1. $\cosθ=−\frac{\sqrt{3}}{2}$