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What are the steps to answering this problem? Sinx(Cosx)/(1+cosx) (1-cosx)= cotx

 Oct 24, 2016
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Verify the following identity:
sin(x) (cos(x))/((1+cos(x)) (1-cos(x))) = cot(x)

Write cotangent as cosine/sine:
(cos(x) sin(x))/((1-cos(x)) (1+cos(x))) = ^?(cos(x))/(sin(x))

Cross multiply:
cos(x) sin(x)^2 = ^?cos(x) (1-cos(x)) (1+cos(x))

Divide both sides by cos(x):
sin(x)^2 = ^?(1-cos(x)) (1+cos(x))

sin(x)^2 = 1-cos(x)^2:
1-cos(x)^2 = ^?(1-cos(x)) (1+cos(x))

(1-cos(x)) (1+cos(x)) = 1-cos(x)^2:
1-cos(x)^2 = ^?1-cos(x)^2

The left hand side and right hand side are identical:
Answer: |(identity has been verified)

 Oct 24, 2016

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