Question

Use the unit circle to find cos (-270°)

Answer 1

Answer:

$\cos (-270\degree)=0$.

Step-by-step explanation:

We want to find the value of $\cos (-270\degree)$.

Note that;

$\cos (-\theta)=\cos (\theta)$

This implies that;

$\cos (-270\degree)=\cos (270 \degree)$

Also 270 degrees is a quadrantal angle.

On the unit circle, $\cos (270\degree)$ is the x-coordinate of the point $(0,-1)$

Hence, $\cos (-270\degree)=0$.