Answer:
Step-by-step explanation:
By taking ( x = 18°)
L.H.S
cos(3x)=sin(2x)
cos(3x) = cos( 3X18°)= cos (54°)
= cos[ 90° - (2x18°)] ∵[ 90°- (2x18°) = 54°]
= ∴ sin ( 2x18°)
As (x = 18°)
= sin (2x) = R.H.S
