Hi Matin Saiyed, let us take R H S
So (cos A + sin A) / (cos A - sin A)
Multiply both numerator and denominator by ( cosA + sin A)
So we get (cos A + sin A)^2 / cos^2 A - sin^2 A
==> (cos^2 A + sin^2 A + 2 sin A cos A) /( cos^2 A - sin^2 A)
==> (1 + sin 2 A) / cos 2 A = L H S [PROVED]
