Question

For what x-value(s) does cos(x) = -1?

A.-270°, -90°, 90°, and 270°

B.-270°, -90°, 0°, 90°, and 270°

C.-180° and 180°

D.-360°, 0° and 360°

Answer 1

Try the answer choices on a calculator and see if they result in -1

Answer 2

c

Answer 3

You are correct.