Question

If cosecA + cot A = b , then prove that cos A = ( b^2- 1)/(b^2+ 1)​

Answer 1

Step-by-step explanation:

From First Sentence multiplying both sides with sin A : cos A = b sin A - 1

Power every side of equation by 2 :

1 - sin^2 (A) = b^2 sin^2 (A) - 2 b sin A + 1

sin A = 2 b / (b ^ 2 + 1)

## cos A = (2b ^ 2 - b ^ 2 - 1) / (b ^ 2 + 1)

=(b^2- 1)/(b^2+ 1)​