Question

How do you evaluate cos (-8pi/3)?

Answer 1

Evaluate `cos ((-8pi)/3)`

Explanation:

Unit circle and Trig Table of Special Arcs -->
#cos ((-8pi)/3) = cos ((-2pi)/3 - (6pi)/3) = cos ((-2pi)/3 - 2pi) = cos ((-2pi)/3) = cos ((2pi)/3) = -1/2#