a) Derive x dx dt in terms of t, using tan(1(dy/dx)) and formula 2 to find d/dt. Then use the chain rule to find d/ds.

b) Considering the curve y=f(x) as the parametric curve x=x, y=f(x), with parameter x, prove that the formula from item a) is obtained.

d2y/dx2 = (1+(dy/dx)^2)^3/2 * d2y/dt2