## Remembering that sin2(θ)=1/2−1/2cos(2θ)\sin^2(\theta) = 1/2 – 1/2\cos(2\theta)?

How do you remember this for integrals? It doesn’t seem obvious and I can never remember it when I come across it in integrals. Answer The double angles should be remembered as follows, 2sin2(θ)=1−cos(2θ)2cos2(θ)=1+cos(2θ). To know which sign for each, remember that ‘sinning’ is bad, hence it leads to −. Reason why you should memorize … Read more