Instructions

  1. Move black points to change the shape of the polygon whose area you want to determine.
  2. The apps contain tips to help find the identities. To see them, move from left to right the corresponding point.

    In case they are available, move from left to right the points corresponding to each proof step.
  3. Observe the changes in the diagram and draw conclusions.
  4. To check your solution, move from left to right the corresponding point.

Remark: After dragging a point from a slider, you may find yourself not able to deselect it. If such a situation occurs (which should be sporadic), just double click on the selected point.