# Math Help - trig question 2

1. ## trig question 2

prove that sin(a+b) = tan a + tan b
cos a cos b

2. Originally Posted by dane
prove that sin(a+b) = tan a + tan b
cos a cos b
Hi dane,

$\frac{\sin (a+b)}{\cos a \cos b} = \frac{\sin a \cos b + \cos a \sin b}{\cos a \cos b}=\frac{\sin a \cos b}{\cos a \cos b}+\frac{\cos a \sin b}{\cos a \cos b}=...$

Simplify this and you should get what you want.