Fewpal
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If 3 cot A = 4, check whether (1-tan2 A)/(1+tan2 A) = cos2 A - sin2 A or not

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Solution:  Given
Cot A=4/3 Or B/P=4/3
Let B=4k and P=3k
So in a right angle triangle with angle A
P2 + B2 =H2
H=5k
Now tan A=1/cot A=3/4
Cos A=B/H=4/5
Sin A=P/H=3/5
Let us take the LHS

RHS = cos2 A -  sin2A= 7/25
So LHS=RHS,so the statement is true

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