Make the following static figures "move".

Construct an animation showing a rod of fixed length slides with its ends upon two fixed perpendicular lines.
What is the envelope formed by the rod?
Find the point of tangency.
Find the locus of a point carried by the rod. (A ladder standing on a smooth floor against a wall slides down. Along what curve does a cat sitting on the ladder move?)
A wooden triangle moves on a plane so that two vertices move along two fixed perpenducluar lines. How does the third vertex move?
Generalized the situation to two fixed lines not necessarily perpendicular to each other.

Construct  an animation displaying a triangle whose vertices travel along three concentric ellipses.