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All formulas for finding trigonometric functions
The formulas of trigonometric function include product and difference formula, product and difference formula, triple angle formula, sine double angle formula, cosine double angle formula, cosine theorem and so on.

1 product sum and difference formula. sinαcosβ=( 1/2)*[sin(α+β)+sin(α-β)]; cosαsinβ=( 1/2)*[sin(α+β)-sin(α-β)]; cosαcosβ=( 1/2)*[cos(α+β)+cos(α-β)]; sinαsinβ=-( 1/2)*[cos(α+β)-cos(α-β)]

2. Sum-difference product formula. sinα+sinβ= 2 sin[(α+β)/2]cos[(α-β)/2]; sinα-sinβ= 2 cos[(α+β)/2]sin[(α-β)/2]cosα+cosβ= 2 cos[(α+β)/2]cos[(α-β)/2]; cosα-cosβ=-2 sin[(α+β)/2]sin[(α-β)/2]

3 triple angle formula. sin3α=3sinα-4sin^3α:cos3α=4cos^3α-3cosα

The trigonometric function relationship between the sum and difference of two angles, sin (α+β) = sin α cos β+cos α sin β; sin(α-β)= sinαcosβ-cosαsinβ; cos(α+β)= cosαcosβ-sinαsinβ; cos(α-β)= cosαcosβ+sinαsinβ; tan(α+β)=(tanα+tanβ)/( 1-tanαtanβ); tan(α-β)=(tanα-tanβ)/( 1+tanαtanβ)