Solve 8cos(5x) = 4 for the three smallest positive solutions

Answer 1

8cos(5x) = 4
cos(5x) = 1/2
so 5x = 60° or cos 5x = 300°
x = 12 or x = 60

the period of cos 5x = 360/5 or 72°
so each of my above answers appear 72° later
from x = 12°, the next 3 answers would be 84°, 156° and 228°
from x = 60, the next 3 answers would be 132°, 204° and 276°

the three smallest answers are
12°, 60° and 84°

If you wanted the answers in radians, I assume you know how to convert.