i need to find (cosθ)\({^2}\) = 1 in the domain \({-360°≤θ <360°}\)

i know i can use the unit circle and quadrantal angles. however, i'm thrown off by the square because i've never encountered a problem like this before? how should i solve it?

for instance, (cos 180)\({^2}\) = -1 isn't possible. however, 180° is a possible answer?

the answers in the textbook are -360°, -180°, 0°, and 180°.

Guest Jan 10, 2019

edited by
Guest
Jan 10, 2019