Show this (differentiation)??? urgent!?

Question

Show that d/dx (sin 2x/ 1 + cos 2x) = k/ 1 + cos 2x, stating the value of the constant k.

Ans: k = 2


Show your workings with explanation..thanks

Answer 1

[sin2x/(1+cos2x)]´= 1/(1+cos2x)^2 * [2(1+cos2x)*cos2x+2sin^2(2x)]= 2/(1+cos2x)^2*(1+cos2x)=
2/(1+cos 2x)
Remember that cos^2+sin^2 =1