Q7 of 48 Page 86

Prove the following:

sin 65° + cos 25° = 2 cos 25°

sin (90˚ – 25˚) + cos 25˚


⇒ cos 25˚ + cos 25˚


⇒ 2 cos 25˚


= R.H.S (Hence, proved.)


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5

Find the values of the following:

(i) tan 12° cot 38° cot 52° cot 60° tan 78°


(ii) tan 5° tan 25° tan 30° tan 65° tan 85°

 6

Express the following in terms of the trigonometric ratios of angles between 0° and 45°.

(i) sin 81° + sin 71°


(ii) tan 68° + sec 68°

 8

Prove the following:

sin 35° sin 55° – cos 35° cos 55° = 0

 9

Prove the following: