This rectangle is cut into five pieces which fit exactly into a triangular outline and also into a square outline where the triangle, the rectangle and the square have equal areas.
Can you cut up any triangle, using straight cuts, and rearrange
the pieces to make a rectangle and a square?
Start by just investigating triangles which have a height of less than twice the base but greater than half the base. Make your own puzzle from card by cutting the triangle into a small number of pieces that can be re-arranged into a rectangle and into a square with the same area.
Suppose you have two triangles with the same area. Do you think you can cut one into pieces which can be re-arranged to form the other?