Question

If θ is an acute angle, solve the following equations for θ:

cos 3 θ (2 sin 2 θ – 1) = 0


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Answer 1

cos3theta(2sin2theta-1)=0

=> 2sin2theta - 1 =0

=> 2sin2theta=1

=>sin2theta=1/2

=>sin2theta=sin30°

=>theta=15°

Answer 2

Answer:

⇒ ${\huge{\underline{\boxed{\orange{\text{θ = 15°}}}}}}$

Step-by-step explanation:

cos3θ•(2sin2theta-1) = 0. < GIVEN >

⇒ 2sin2θ - 1 = 0

⇒ 2sin2θ = 1

⇒ sin2θ = 1/2

⇒ sin2θ = sin30° < sin30° = 1/2 >

Comparing both sides,We get

⇒ 2θ = 30°

⇒ θ = 15°

${\boxed{\green{\text{Hence,The Value of θ = 15°}}}}$