Use the slider to adjust the radius between 1 and 6.
	Move the cursor over the picture to start the animation.
	Move the cursor over the picture to start the animation.
	The level curves of f(x,y)=x2+y2 and the parabola g(x,y)=y2-x-9/2=0.
	The graph of f(x,y)=x2+y2, where x and y are restricted to the parabola g(x,y)=y2-x-9/2=0 below.