Solve the equation 8 cos^2 X -2 =0 given that 180< or equal to X <or equal to 360 degrees.

Answer 1

8cos^2X - 2 = 0
8cos^2x = 2
cos^2x = 2/8 = 0.25
cosx = sqrt(0.25) = 0.5
Xr = 60o = Reference angle.

X-Xr = 180
x-60 = 180
X = 180+60 = 240o.