A tennis ball is served from directly above the baseline (assume
the ball travels in a straight line). What is the minimum height
that the ball can be hit at to ensure it lands in the service area?
If the sides of the triangle in the diagram are 3, 4 and 5, what is
the area of the shaded square?
How many rectangles can you find in this shape? Which ones are
differently sized and which are 'similar'?
Plex lets you specify a mapping between points and their images.
Then you can draw and see the transformed image.