Refresher - Addition Formulas for Sine and Cosine and Their Proofs

You can use the following sum and difference formulas for sine and cosine to evaluate trigonometric functions, verify identities, and solve trigonometric equations.

${\displaystyle sin(u+v)=sinu}$ ${\displaystyle cosv+cosu}$ ${\displaystyle sinv}$

${\displaystyle sin(u-v)=sinu}$ ${\displaystyle cosv-cosu}$ ${\displaystyle sinv}$

${\displaystyle cos(u+v)=cosu}$ ${\displaystyle cosv-sinu}$ ${\displaystyle sinv}$

${\displaystyle cos(u-v)=cosu}$ ${\displaystyle cosv+sinu}$ ${\displaystyle sinv}$