1.Express the trigonometric ratios sin A, sec A and tan A in terms of cot A.
Solution:
2.Write all the other trigonometric ratios of ∠A in terms of sec A.
Solution: 
3.Choose the correct option. Justify your choice.
(i) 9 sec² A – 9 tan² A = ……
(A) 1
(B) 9
(C) 8
(D) 0
(ii) (1 + tan θ + sec θ) (1 + cot θ – cosec θ) = ………..
(A) 0
(B) 1
(C) 2
(D) -1
(iii) (sec A + tan A) (1 – sin A) = ………….
(A) sec A
(B) sin A
(C) cosec A
(D) cos A
(iv) 1+tan2A1+cot2A = ………..
(A) sec² A
(B) -1
(C) cot² A
(D) tan² A
Solution: 
4.Prove the following identities, where the angles involved are acute angles for which the expressions are defined. 
Solution: 
