Here you have to type the equation of the desired curves in parametric form. A parametric equation is an equation, equation of X, Y and Z is expressed in terms of a common parameter “t”. As you can see from the given example of creating the circular datum curve of radius 4 by typing the following codes below the dashed line of the equation editor:
x=4*cos(t*360)
y=4*sin(t*360)
z=0