4. a) Write down the vector parametrization of a curve in R with constant speed 3 and constant curvature 4. Briefly justify how you came up with this equation. Comment on the uniqueness of such a curve (i.e. are there other curves with these properties?). b) Write down the Frenet-Serret equations for curves in R3. Consider the curve parametristd by r(t) = (sint - cost) , NI- (sint + cost) , V2 IER. Calculate T, N. B, x and + for this curve. Comment on the shape of the curve (a sketch is not required)