Running into this problem, im trying to graph concentric circles (think planets) with a set radius and a set amount of time used to complete one orbit. I am using parametric equations with t being a value of time in terms of one complete orbit. However, when I try to graph these circles using plots[multiple] I get error codes. Heres my text~ We have our 5 planets, A - E orbiting around the sun affixed at the origin. We can easily graph these together to give us an idea of the orbit and time required to complete one. > plots[multiple](plot, > [0.71 cos(2.985074627 Pi t), 0.71 sin(2.985074627 Pi t), t = 0 .. 67],