Find the locus that will create an ellipse.[br][br]An ellipse is the set of points such that the sum of the distances from two points is constant.
1) Create a circle with center at A with defined radius d. [br]2) Create another circle centered at B and with radius a-d.[br]3) Move the slider until the circles intersect at two points. Label those two points C and D. [br]4) Create segments AC, AD, BC and BD.[br]5) Unselect the circles so that they do not show up. [br]6) Right click on C and D and turn on the trace.[br]7) Move the slider around to see the points C and D "create" an ellipse.
Given the definition of an ellipse (see above) why did we construct the circles in this way?[br]Hint: How did we define our radii?