# Verifying that the equation is an identity

• Apr 7th 2008, 10:59 PM
Thelema
Verifying that the equation is an identity
sin(180-x)-cotxsin(x-90)=cscx
• Apr 8th 2008, 03:31 AM
topsquark
Quote:

Originally Posted by Thelema
sin(180-x)-cotxsin(x-90)=cscx

$sin(a \pm b) = sin(a)~cos(b) \pm sin(b)~cos(a)$

So:
$sin(180 - x) = sin(180)~cos(x) - sin(x) ~cos(180) = sin(x)$
and
$sin(x - 90) = sin(x)~cos(90) - sin(90)~cos(x) = -cos(x)$

So your left hand side becomes:
$sin(x) + cot(x)~cos(x)$

Can you take it from here?

-Dan