Q. 8 B5.0( 2 Votes )

# If θ = 30°, verify that :cos3θ = 4cos3θ – 3cosθ

Given: θ =30o

Now, LHS = cos 3(30o)

cos 90o

= 0

Now, RHS = 4 cos3 θ - 3 cos θ

4 cos3 (30o) - 3 cos (30o)

= 0

LHS = RHS

Hence Proved

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