Thread: Trig identity

Hi, got an identity I need to prove.

[tex]\frac{(cos 3A - cos 7A)} / {(sin 7A+sin 3A)}=tan 2A[tex]

Any help would be appreciated.

Thanks in advance.

-deleted-

Originally Posted by jo74

Hi, got an identity I need to prove.

[tex]\frac{(cos 3A - cos 7A)}{(sin 7A+sin 3A)}=tan 2A[tex]

Any help would be appreciated.

Thanks in advance.

try to solve it with these





note sin(-x) = - sin(x)