Question

Find all solutions to the equation. cos x = -1/2

Answer 1

You didn't add the range. I'll use (0<x<2π)

cosx = -1/2

x=-cos-¹(1/2)

x= -60°

Cosine is negative in the second and 3rd quadrants

180-x ---- Second quadrant

x+180 ----- 3rd quadrant

So

Our answer

180-(-60)=240° or 4π/3 second quad

180+(-60) = 120° or 2π/3---- 3rd quad

Answer 2

^^

Explanation: