Skip to main contentSkip to solution

If x=a(1−cos⁡θ),y=a(θ+sin⁡θ)x=a(1-\cos\theta), y=a(\theta+\sin\theta) then d2ydx2\frac{d^2y}{dx^2} is equal to

Solution

✅ Correct Option: 2

dxdθ=asin⁡θ\frac{dx}{d\theta}=a\sin\theta, dydθ=a(1+cos⁡θ)\frac{dy}{d\theta}=a(1+\cos\theta), so dydx=1+cos⁡θsin⁡θ=cot⁡θ2\frac{dy}{dx}=\frac{1+\cos\theta}{\sin\theta}=\cot\frac{\theta}{2}. Then d2ydx2=−12csc⁡2θ2asin⁡θ=−12csc⁡2θ22asin⁡θ2cos⁡θ2=−14acsc⁡3θ2sec⁡θ2\frac{d^2y}{dx^2}=\frac{-\frac12\csc^2\frac\theta2}{a\sin\theta}=\frac{-\frac12\csc^2\frac\theta2}{2a\sin\frac\theta2\cos\frac\theta2}=-\frac{1}{4a}\csc^3\frac\theta2\sec\frac\theta2.

Keyboard Shortcuts

  • Left arrow: Previous question
  • Right arrow: Next question
  • S key: Jump to solution
  • Q key: Jump to question