Question: sliding ladder animation

January 10 2013 brian bovril 444

can someone assist me to animate the following:

 A ladder is leaning against a wall. The base of the ladder starts sliding away from the wall, with the top of the ladder sliding down the wall. As the ladder slides, you watch the red point in the middle of the ladder. What figure does the red point trace? (a circle)

I tried this:

animate(plot, [A*(-3*x+6), x = 0 .. 5], A = 3 .. -3);

Please Wait...