Find $d\frac{y}{d}x$ and $d^2\frac{y}{d}{x}^2.$

$\frac{dy}{dx}=$

$\frac{d^{2}y}{d{x}^2}=tx=2sin(t),y=3cos(t),0$

$\frac{dy}{dx}=$

$\frac{d^{2}y}{d{x}^2}=$

$$

$$

For which values $oftis$ the curve concave upward? $(Enter$ your answer using interval notation.$)$