Question

prove : cos2A + 1 upon 1 - cos2A = cot²A.. please help me anyone

Answer 1

Note: We know that cos 2 theta = 2 cos^2theta - 1 (or) 1 - 2 sin^2theta.

LHS:

$\frac{cos2A + 1}{1 - cos2A}$

$\frac{2 cos^2A - 1 + 1}{1 - (1 - 2sin^2A)}$

$\frac{2cos^2A}{1 - 1 + 2sin^2A}$

$\frac{2cos^2A}{2sin^2A}$

$\frac{cos^2A}{sin^2A}$

cot^2A.


LHS = RHS.

Hope this helps!