Question

If A = 30°; show that :
(i) sin 3A
= 4 sin A sin (60° - A ) sin (60° + A )
(ii) (sin A - cos A ) ² = 1 - sin 2 A
(iii) cos 2A = cos⁴ A - sin⁴ A
(iv) 1 - cos 2 A / sin 2A = tan A
(v) 1 + sin 2A + cos 2 A / sin A + cos A = 2 cos A .
(vi) 4 cos A cos (60°- A ) cos (60°+A ) = cos 3A
(vii) cos³A - cos 3A/cos A + sin³ A + sin 3A/ sin A = 3​

Answer 1

Step-by-step explanation:

substitute A=30 in equations

sin90=4×1/2×1/2×1

1=1