Answer
$\frac{dy}{dx} = (2x \pi)sec^{2}(\pi x^{2})$
Work Step by Step
$\frac{dy}{du} = \frac{d (tan u)}{du} = sec^{2}u$
and,
$\frac{du}{dx} = \frac{d (\pi x^{2})}{dx} = 2x \pi$
So,
$\frac{dy}{dx} = \frac{dy}{du} * \frac{du}{dx}$
$\frac{dy}{dx} = (2x \pi) sec^{2} u$
$\frac{dy}{dx} = (2x \pi)sec^{2}(\pi x^{2})$
