Answer:
Step-by-step explanation:
By taking ( θ = 18°)
L.H.S
cos(3θ)=sin(2θ)
cos(3θ)= cos( 3X18°)= cos (54°)
= cos[ [tex]\frac{\pi }{2}[/tex] - (2x18°)] ∵[ [tex]\frac{\pi }{2}[/tex] - (2x18°) = 54°]
= ∴ sin ( 2x18°)
As θ = 18°
= sin (2θ) = R.H.S
