Evaluate each value as a trigonometric function of an angle in Quadrant 1.

Question

#1 cos (27pi/8)

Answer 1

27 pi/8 = 3 pi + 3 pi/8
that is 180 degrees + 67.5 degrees
that is in quadrant 3 where cos is negative
so
-cos 3 pi/8 radians
or
-cos 67.5 degrees