Find all values of in radians with 2 2 such that cos 1 Th

Find all values of in radians with -2 < < 2 such that cos() = 1 There may be more than one answer. Please list all answers in the indicated range, separating them by commas. Note that < means the endpoints of the range are excluded.

Solution

cos() = 1

given  -2 < < 2

in the given interval cos() = 1 occurs only when =0