Our goal will be to draw an equilateral triangle using the line segment given below. First, draw a circle centered at the green endpoint passing through the red point. To do so, select "Circle" from the Choice Menu in the lower left hand corner of the applet and follow the on-screen instructions. Next, draw a circle centered at the red point passing through the green point.

Notice that the two circles you have drawn intersect in two distinct places. To draw these points of intersection, select "Intersection" from the Choice Menu and follow the instructions.

Next, pick one of the points of intersection and draw a line segment between it and each of the green and red dots. To do so, select "Line Segment" from the Choice Menu and follow the instructions.

You have just drawn an equilateral triangle. Can you explain why? Drag the red and green points around the screen to see how the above construction changes.