Sum and Difference Formulas in Trigonometry

This is a list of the sum and difference formulas involving the sine,cosine and tangent functions used in trigonometry.

Review

Sum Formulas


  1. sin(x + y) = sin x * cos y + cos x * sin y

  2. cos(x + y) = cos x * cos y - sin x * sin y

  3. tan(x + y) = [tan x + tan y] / [1 - tan x * tan y]




Difference Formulas


  1. sin(x - y) = sin x * cos y - cos x * sin y

  2. cos(x - y) = cos x * cos y + sin x * sin y

  3. tan(x - y) = [tan x - tan y] / [1 + tan x * tan y]

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  • Trigonometric Formulas and Their Applications
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  • Trigonometric Identities and Their Applications

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