Posted by **Haley** on Wednesday, January 12, 2011 at 11:04pm.

verify that the equation is an identity:

(1-cosX)/(1+cosX) = (cscX-cotX)^2

- Math -
**Reiny**, Wednesday, January 12, 2011 at 11:11pm
LS = (1- cosx)/(1 + cosx) [(1-cox)/(1-cosx)]

= (1-cosx)^2/(1-cos^2x)

RS = (1/sinx - cosx/sinx)^2

= ((1-cosx)/sinx)^2

= (1-cosx)^2 /(sin^2x)

= (1-cosx)^2/(1-cos^2)

= LS

- Math -
**Haley**, Wednesday, January 12, 2011 at 11:32pm
thanks. How would you know how to do similar problems? Where should i start when verifying trig equations?

- Math -
**Reiny**, Wednesday, January 12, 2011 at 11:42pm
Usually start with the complicated looking side and try to reduce to the simpler side.

In this case I worked on both sides.

Also I often change everything to sines and cosines, unless I recognize a popular identity.

How did I know where to start??

Let's say doing this for 35 years and doing thousands of these could be the reason, lol

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