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May 29, 2015

Homework Help: Trig!

Posted by Elle on Tuesday, September 27, 2011 at 12:21pm.

The identities cos(a-b)=cos(a)cos(b)sin(a)sin(b) and sin(a-b)=sin(a)cos(b)-cos(a)sin(b) are occasionally useful. Justify them. One method is to use rotation matricies. Another method is to use the established identities for cos(a+b) and sin (a+b).

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