Trigonometric product and difference calculator

The double angle formula is a very practical formula in trigonometric functions. It is to express the trigonometric functions of the double angle using the trigonometric functions of the angle itself. It can be used to simplify the calculation formula and reduce the number of times the trigonometric functions are calculated in calculations. It is also widely used in engineering.

sinαsinβ=-1/2[cos(α+β)-cos(α-β)]

cosαcosβ=1/2[cos(α+β)+cos(α-β)]

sinαcosβ=1/2[sin(α+β)+sin(α-β)]

cosαsinβ=1/2[sin(α+β)-sin(α-β)]