1.   Evaluate :
	(i) ${sin 18°}/{cos 72°}$   (ii) ${tan 26° }/{cot 64°}$    (iii)  cos 48° – sin 42°   (iv)  cosec 31° – sec 59°

2.   Show that :
(i)   tan 48° tan 23° tan 42° tan 67°  = 1;    (ii)   cos 38° cos 52° – sin 38° sin 52° = 0

3.   If tan 2A = cot (A – 18°), where 2A is an acute angle, find the value of A.

4.   If tan A = cot B, prove that A + B = 90°.

5.   If sec 4A = cosec  (A – 20°), where 4A is an acute angle, find the value of A.

6.   If A, B and C are interior angles of a triangle ABC, then show that
		sin$({B+C}/2)$=cos$(A/2)$
		
7.   Express sin 67° + cos 75° in terms of trigonometric ratios of angles between 0° and 45°.

Solution