Question

7. If 2 cos 2A = root 3 and A is acute, find
(i) A
(ii) sin 3A
(iii) sin2 (75° – A) + cos2 (45° + A)​

Answer 1

I think sin 3A I am not sure of the question because I am in 7 std so yay

Answer 2

Answer:

(i) cos 2A = root 3/2

cos 2A = cos 30°

A = 15°

(ii) sin 3A = sin 3(15°)

= sin 30°

= 1/ root 2

(iii) sin 2 (75° - 15°) + cos 2(45° + 15°)

sin 180 + cos 180 = -1