Barack Obama, the 44th US. president is always confused in trigonometry Donald Trump give him a question in which cosecθ - sinθ = x3 and secθ - cosθ = y3. Then, find the value of x2y2(x2 + y2) for him. 

Barack Obama, the 44th US. president is always confused in trigonometry Donald Trump give him a question in which cosecθ - sinθ = x3 and secθ - cosθ = y3. Then, find the value of x2y2(x2 + y2) for him.  Correct Answer 1

Given∶

cosec

θ - sin

θ = x3 and sec

θ - cos

θ = y3

Formula Used∶

 

Basics of Trigonometry.

sin2θ + cos2θ = 1

Calculation∶

cosec

θ - sin

θ = x3

⇒ 1/sin

θ - sin

θ = x3

⇒ (1 - sin2θ ) / sinθ = x3

⇒ cos2θ /sinθ = x3

⇒ x = (cos2θ /sinθ )1/3      ---(1)

Also, secθ - cosθ = y3

⇒ 1/cosθ - cosθ = y3

⇒ (1 - cos2θ )/cosθ = y3

⇒ sin2θ /cosθ = y3

⇒ sin2θ /cosθ = y3

⇒ y = (sin2θ /cosθ )1/3      ---(2)

Now take,

⇒ (cos2θ /sinθ)2/3(sinθ/cosθ)2/3     

⇒ (cos2θ.sin2θ/sinθ.cosθ]2/3

⇒ (cosθ.sinθ)2/3

⇒ (cosθ.sinθ)2/3[(cos2θ / sinθ)2/3+ (cosθ.sinθ)2/3(sin2θ /cosθ )2/3

⇒ (cosθ.sinθ.cos2θ/sinθ)2/3+ (cosθ.sinθ.sin2θ/cosθ)2/3

⇒ (cos3θ)2/3 + (sin3θ)2/3

⇒ cos2θ + sin2θ

⇒ 1

∴ The correct option is 4.

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