Please tell me how to find an equation for the line tangent to the curve at the given point.

also tell me how to find the value of d^2y/dx^2 at that point

(Parametric curves)

1)

x=4sin(t),y=2cos(t),t0=4

2)

x=t+1,y=3t,t0=3

Please tell me how to find the points on the curve where the tangent is horizontal or vertical

3)

x=2cos,y=sin2