1.

9.4) =show that: 4sinθcos^3θ - 4cosθ sin^3θ =sin4θ​

Answer»

Step-by-step EXPLANATION:

To PROVE : 4sinθcos³θ - 4cosθ sin³θ = sin4θ​

take LHS

= 4sinθcos³θ - 4cosθ sin³θ

= 2sinθcosθ (2cos²θ-2sin²θ)        

= sin2θ. 2 .(cos²θ - sin²θ)       [ ∵ sin2θ = 2sinθcosθ ]

= 2 sin2θ cos2θ                     [ ∵ cos2θ = cos²θ - sin²θ ]

= sin2(2θ)

= sin4θ

= RHS

=> LHS =  RHS.

Hence proved



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