Trig Sum of Two Angles

Tri functions of (α+β) and (α-β)

Click on formula to see proof.

sin(α+β) = sinαcosβ + cosαsinβ

sin(α-β) = sinαcosβ - cosαsinβ

cos(α+β) = cosαcosβ - sinαsinβ

cos(α-β) = cosαcosβ + sinαsinβ

tan(α+β) = (tanα + tanβ) / (1 - tanα * tanβ)

tan(α-β) = (tanα - tanβ) / (1 + tanα * tanβ)

Factor Formulae

Converting the sum of two trig functions to the product of two trig functions.