To verify the given identity, we work with the value on the right hand side. That is:
2 (csc^2 (x)) (tan x)
We know that csc is the inverse of sine and that tan = sin / tan, therefore:
= 2 (1 / sin^2 (x)) (sin x / cos x)
Cancelling sin x:
= 2 (1 / sin x) (1 / cos x)
Multiplying both the numerator and denominator by 2:
= 4 / 2 sin x cos x
From the trigonometric identities, 2 sin x cos x = sin 2x, therefore:
= 4 / sin 2x
= 4 csc 2x
Hence, it is proven.