Proving Trigonometric Identities

1. sec^2x + csc^2x= (sec^2 x)(csc^2 x)
2. sin ^3 x / sin x - cos 3x / cos x = 2
3. 1- cos x/ sin x= sin x/ 1+ cos x
4. 2 sin x cos ^2 (x/2)- 1/x sin (2x) = sinx
5. cos 2 x + sin x/ 1- sin x= 1+ 2 sin x

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