Prove that cot2A=cot^2A-1/2cotA

Steps to prove cot2A=cot^2A-1/2cotA

Take L.H.S cot2A

= cot2A

= cot(A+A)

= cotA.cotA-1/cotA+cotA      [cot(A+B)=cotA.cotB-1/cotA+cotB]

= cot^2A-1/2cotA

= R.H.S

∴ Hence we proved cot2A=cot^2A-1/2cotA

Detailed Information:

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