16. Parametric Equations & Polar Coordinates

73–76. Tangent lines Find an equation of the line tangent to the curve at the point corresponding to the given value of t.

x=cos t+t sin t,y=sin t−t cos t; t=π/4

Write the equation of the tangent line in cartesian coordinates for the given parameter $t$.

$x=8\cos t$, $y=6\sin t$, $t=\frac{\pi }{4}$

Find $\frac{d^{2}y}{d{x}^2}$ for the parametric curve at the given point.

$x=8\cos t$, $y=6\sin t$, $t=\frac{\pi }{4}$