If $x=a(t+\sin t), y=a(1-\cos t)$, then $\frac{d y}{d x}=$

If $x=a(t+\sin t), y=a(1-\cos t)$, then $\frac{d y}{d x}=$
  1. $\tan \frac{t}{2}$
  2. $-\frac{t}{2} \tan t$
  3. $\frac{1}{2} \tan t$
  4. $-\tan \frac{t}{2}$

Solution

$\begin{aligned} & x=a(t+\sin t) \text { and } y=a(1-\cos t) \\ & \therefore \frac{d x}{d t}=a(1+\cos t) \text { and } \frac{d y}{d t}=a(\sin t) \\ & \therefore \frac{d y}{d x}=\frac{\left(\frac{d y}{d t}\right)}{\left(\frac{d x}{d t}\right)}=\frac{a \sin t}{a(1+\cos t)}=\frac{2 \sin \frac{t}{2} \cos \frac{t}{2}}{2 \cos ^2 \frac{t}{2}}=\tan \frac{t}{2} \end{aligned}$

Asked in: MHT CET 2021 (20 Sep Shift 2)

Practice more Differentiation questions on Aicharya