Question

Proove:

$\frac{secA-1}{secA+1}=\frac{1-cosA}{1+cosA}$

Answer 1

$\frac{\sec A-1}{\sec A+1}=\frac{1-\cos A}{1+\cos A}$

L.H.S:

$\frac{\sec A-1}{\sec A+1}$

$=\frac{\frac{1}{\cos A}-1}{\frac{1}{\cos A}+1}$

$=\frac{\frac{1-\cos A}{\cos A}}{\frac{1+\cos A}{\cos A}}$

$=\frac{1-\cos A}{1+\cos A}=$R.H.S.