This demo displays the circle given by X(t) = (a,b) + (Rcos(t), Rsin(t)). To change (a,b), click and drag on the point labeled "(a,b)". To change R, click and drag the point labeled "R". To move the point X(t0) along the circle use the arrow buttons ([<], [>], [<<], [>>]), which have the same function as in the first two demos. As in earlier demos, there are "Show entire curve", "Show position vector X(t0)", and "Show Color Spectrum" options.