Find all angles, 0≤θ<360, that satisfy the equation below, to the nearest 10th of a degree. 2\cos^2\theta -10=-\cos\theta -9 2cos 2 θ−10=−cosθ−9

Question

Find all angles, 0∘≤θ<360∘, that satisfy the equation below, to the nearest 10th of a degree.

2cos2θ−10=−cosθ−9

Answer 1

Convert cos 2θ to (2 cos² θ - 1), factor and use zero product rule from Algebra.