Question

Solve the equation cos2x = -1\2, for 0 < x < 360°.​

Answer 1

x = 60°, 120°

Explanation:

If we let
`t=2x`, our equation now becomes
`cos(t)=-1/2`, which is true for two values of t: 120° and 240°. Since t = 2x, we can say that
`120^(\circ)=2x` and
`240^(\circ)=2x`, and therefore
`x = 60^(\circ)` and
`x=120^(\circ)`