I'm having a few problems with these questions... any help is appreciated! Thanks!

find $\displaystyle d^2y \over{dx^2}$ of $\displaystyle x = \sqrt{t}$; $\displaystyle y = 2t + 4 $ at $\displaystyle t = 1 $

Find the arc length of the curve $\displaystyle x = e^t cos(t)$, $\displaystyle y = e^tsin(t)$, $\displaystyle 0 <= t <= {\pi\over{2}}$