Proof of the Difference Formula for Sine and of the Addition Formula for Cosine
Proof of the Difference Formula for Sine and of the Addition Formula for Cosine
This Demonstration shows a proof of the difference formula for sine, and a proof of the addition formula for cosine, using the formula .
sin(α-β)=sin(α)cos(β)-cos(α)sin(β)
cos(α+β)=cos(α)cos(β)-sin(α)sin(β)
cos(α+β)=sin(π/2-(α+β))