This is an important question taken from the Book ML Aggarwal, Avichal publication, class 10th and, chapter 18
We have to proof that
(i) sin A/ (1 + cos A) = (1 – cos A)/ sin A
(ii) (1 – tan2 A)/ (cot2 A – 1) = tan2 A
(iii) sin A/ (1 + cos A) = cosec A – cot A
Class10th, chapter 18, ques no 15, trigonometric identities
Solution:
(i) L.H.S. = sin A/ (1 + cos A)
On multiplying and dividing by (1 – cos A), we have