The tangent to the curve $x=a(\theta-\sin \theta), y=a(1+\cos \theta)$ at the points $\theta=(2 n+1) \pi, n \in Z$ are parallel to
Answer & explanation
Correct answer: option 1
$\frac{d y}{d x}=\frac{-\sin \theta}{1-\cos \theta}$
∴ $\frac{d y}{d x}=0$ for $\theta=(2 n+1) \pi$
∴ The tangent is parallel to x-axis.