Answer
$f_t=- 2\pi \sin(2πt-\alpha)$
and
$f_α=\sin(2πt-\alpha)$
Work Step by Step
Our aim is to take the first partial derivatives of the given function $f(x,y)$ with respect to $t$, by keeping $\alpha$ as a constant, and vice versa:
$f_t=- 2\pi \sin(2πt-\alpha)$
and
$f_{\alpha}=(-1) \times -\sin(2πt-\alpha)\sin(2πt-\alpha)$
