1) Plot the folium of descartes x^3+y^3-3xy=0 

a) Can you make up a curve from a relation that satisfies xRy iff yRx

2) Consider functions not on rectangular but polar coordonates: 

      R=f(theta) where theta is greater or equal to zero but below 360 degree

       Here, theta is the angle from the radial axis R 

        Sketch some curves by choosing a random expression of f (polynomials, sine, square-root, absolute value etc) and sketch the results

What is the visual rule that shows you the curve is the graph of a polar function r=f(theta) analogus to the vertical line rule for rectangular functions y=f(x)?