# Thread: Equations Involving Multiple Angles

1. ## Equations Involving Multiple Angles

Hi there,

I'm currently revising for my higher exam, and am a bit confused as to how to solve this equation.

sin2x-cosx=0 for 0≤x≤360

I have managed to get 30 and 150 degrees, but the answers tell me I should also be getting 90 and 270 degrees, and I'm unsure how to go about getting those answers.

$\sin(2x)-\cos(x)=2\sin(x)\cos(x)-\cos(x)=\cos(x)(2\sin(x)-1)=0$