csc(2x) = csc(x)/(2cos(x))
1/(sin(2x)) = csc(x)/(2cos(x))
1/(2*sin(x)*cos(x)) = csc(x)/(2cos(x))
(1/sin(x))*1/(2*cos(x)) = csc(x)/(2cos(x))
csc(x)*1/(2*cos(x)) = csc(x)/(2cos(x))
csc(x)/(2*cos(x)) = csc(x)/(2cos(x))
The identity is confirmed. Notice how I only altered the left hand side (LHS) keeping the right hand side (RHS) the same each time.