Parabola

Unlike ellipses, parabolas do not lend themselves to simple mechanical drawing aids. The ones occasionally described in texts work crudely. Templates are hard to find. The two best methods for drawing parabolas both involve locating points on the parabola and connecting those points either by eye, or with the help of a draftsman's french curve.

The equation of 4ky = x² or y = x²/4k can be used to plot points on graph paper. The parameter K, which represents the distance from the focus to the vertex, should be chosen to make the parabola appropriately "sharp" or broad. A table of ordered paris (x,y) will help in point plotting. Enough points should be plotted, especially near the vertex where the curvature of the parabola changes most rapidly, that a smooth, accurate curve can be sketched.