Question

what is the answer please answer it

Answer 1

Answer:

Step-by-step explanation:

sin B = 1/2

sin B = sin 30

Therefore ,

B = 30 -----( 1 )

according to the problem given,

LHS = 3(cos B ) - 4 Cos³ B

= - ( 4cos³ B - 3 cos B )

[ since cos 3x = 4cos³ x - 3 cos x ]

= - cos 3B

= - cos ( 3 × 30) from ( 1 )

= - cos 90

= 0

= RHS