SOLUTION: Prove the identity cot A = sin2A/1-cos2A.

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Question 960754: Prove the identity cot A = sin2A/1-cos2A.
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
cot%28A%29%22%22=%22%22sin%282A%29%2F%281-cos%282A%29%29

Use these two identities on the right side: 

              sin%282theta%29=2sin%28theta%29cos%28theta%29 and cos%282theta%29=1-2sin%5E2%28theta%29

     %22%22=%22%22%282sin%28A%29cos%28A%29%29%2F%281-%281-2sin%5E2%28A%29%29%29

     %22%22=%22%22%282sin%28A%29cos%28A%29%29%2F%281-1%2B2sin%5E2%28A%29%29

     %22%22=%22%22%282sin%28A%29cos%28A%29%29%2F%282sin%5E2%28A%29%29

     %22%22=%22%22


     %22%22=%22%22cos%28A%29%2Fsin%28A%29

     %22%22=%22%22cot%28A%29
Edwin