Question 605601
How do you verify that (cot of alpha) / (csc of alpha -1) = (csc of alpha +1) / (cot of alpha)?
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cot/(csc - 1) = (csc + 1)/cot
Cross multiply 
cot^2 = csc^2 - 1
That's an identity, so QED.
Or multiply thru by sin^2
--> cos^2 = 1 - sin^2, the Pythagorean identity.