16 cos2 x − 4 = 0

Question

Solve the equation. (Enter your answers as a comma-separated list. Use n as an integer constant. Enter your response in radians.)

Answer 1

cos2x = 4/16 = 1/4

cos2x = cos^2x - sin^2x = 1-2sin^2x = 1/4

2sin^2x = 1-1/4 = 3/4

sin^2x = 3/8

sinx = sqr(3/8) =

x = about 37.76 degrees

16cos(75.52) - 4 = 0

16(1/4) - 4 = 0

4-4 = 0