1. Find an equation for the line in the xy−plane that is tangent
to the curve at the point corresponding to the given value of t.
Also, find the value of d^2y/dx^2 at this point. x=sec t, y=tan t,
t=π/6
2. Find the length of the parametric curve: x=cos t, y=t+sin t,
0 ≤ t ≤ π. Hint:To integrate , use the identity, and
complete the integral.