Compute sin 2θ, cos 2θ (all three forms) and tan 2θ from θ.
Input
Answer
Steps
Why it works
Double-angle formulas are the sum formulas with A=B=θ: sin2θ = 2sinθcosθ; cos2θ = cos²θ−sin²θ = 2cos²θ−1 = 1−2sin²θ (three interchangeable forms); tan2θ = 2tanθ/(1−tan²θ). The cos forms are what power-reduction uses.
