Friday, August 1, 2014

Prove the following identity: (csc^2) x = (2 sec 2x) / (sec 2x - 1)

We have to  prove that (csc x)^2 = (2 sec 2x) / (sec 2x -
1)


(2 sec 2x) / (sec 2x -
1)


=> [2*(1/ cos 2x)] / [((1/ cos 2x) -
1)]


=> [2*(1/ cos 2x)] / [((1 - cos 2x)/ cos
2x)]


=> 2/ (1 - cos
2x)


=> 2 / ( 1- (1 - 2 (sin
x)^2))


=> 2 / [ 1 - 1 + 2(sin
x)^2]


=> 2 / 2 (sin
x)^2


=> cosec x


This
proves that the right hand side = left hand
side


Therefore we prove that (csc x)^2 = (2
sec 2x) / (sec 2x - 1)

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