CUET Preparation Today
If sinθ + cosec θ = 5 , find the value of sin3θ + cosec3θ. |
120 105 110 115 |
110 |
Formula I → [cosec = \(\frac{1}{sinθ}\)] Formula II → [If x + \(\frac{1}{x}\) = n and x3 + \(\frac{1}{x^3}\) = n3 - 3n] sinθ + \(\frac{1}{sinθ}\) = 5 ⇒ sin3θ + \(\frac{1}{sin^3θ}\) = (5)3 - 3 × 5 ⇒ sin3θ + cosec3θ = 125 - 15 = 110 |
