Question

if sinθ=1/2 then find 3cosθ-4cosθ^3=0​

Answer 1

Correct Question- If sinθ = 1/2 then show that 3cosθ - 4cos³θ = 0.

Answer:

sin θ = 1/2

sin θ = sin 30

Therefore ,

θ = 30 ... (1)

According to the problem given,

LHS = 3cosθ - 4cos³ θ

= - ( 4cos³ θ - 3 cos θ )

= - cos 3θ

= - cos ( 3 × 30)... from ( 1 )

= - cos 90

= 0

= RHS

Hence, Proved.

Answer 2

Answer:

LHS=RHS

0=0

hence proved