Cos2(theta)=Cos^2(theta)-1/2

Question

Solve the given equation. (Enter your answers as a comma-separated list. Let k be any integer. Round terms to three decimal places where appropriate. If there is no solution, enter NO SOLUTION.)

cos(2θ) = cos2(θ) − 1/2

 

Answer 1

cos(2t) = cos^2 - 1/2

2cos^2 - 1 = cos^2 - 1/2

cos^2 - 1 = -1/2

cos^2 = 1/2

cos = +or- sqrt(2)/2

angle is flavors of 45 degrees

45, 135, 225, 315