# Tangled with differentials

Calculus Level 4

If $x = t \cos t$ and $y = t + \sin t$, then find $\dfrac{d^2x}{dy^2}$ at $t = \dfrac \pi 2$.

If the answer is in the form $(-1)^a \left(\dfrac{π + b}{c}\right)$, where $a$ is the smallest possible whole number satisfying the solution and $b$ and $c$ are natural numbers, input the answer as $a+b+c$.

For more interesting problems, try out my set No Problemo

×