Trig | Bored Of Studies

turnerloos

TAFE Executive Officer

Jan 14, 2015

Hey, how would i convert this:
cos((a-b)/2)sec(b) - sin((a+b)/2)tan(b)
into:
cos((a+b)/2)

Thanks

$$ The expression $=\frac{\cos\frac{\alpha-\beta}{2}}{\cos\beta}-\frac{\sin\frac{\alpha+\beta}{2}\sin\beta}{\cos \beta}=\frac{\cos\left(\frac{\alpha+\beta}{2}-\beta\right)-\sin\frac{\alpha+\beta}{2}\sin\beta}{\cos\beta}= \frac{\cos\frac{\alpha+\beta}{2}\cos\beta+ \sin\frac{\alpha+\beta}{2}\sin\beta-\sin\frac{\alpha+\beta}{2}\sin\beta}{\cos\beta}= \cos\frac{\alpha+\beta}{2}$

Last edited: Jan 14, 2015

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turnerloos

TAFE Executive Officer

FrankXie

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