Consider the parametric curve given by

(a) Find $dy/dx$ and $d^2y/dx^2$ in terms of $t$.

$dy/dx$ =

$d^2y/dx^2$ =

(b) Using "less than" and "greater than" notation, list the $t$-interval where the curve is concave upward.

Use upper-case "INF" for positive infinity and upper-case "NINF" for negative infinity. If the curve is never concave upward, type an upper-case "N" in the answer field.

$t$-interval: $< t <$