Polygon Plotter

(use with UCSMP Advanced Algebra, Lessons 4-1, 4-4, 4-6, 4-7, 4-9)

If you can't see the demo above, click here.


This interactive applet allows you to manipulate polygons using matrices. You can enter a polygon or line segment at the top left by first selecting the number of vertices and then entering the locations for each vertex and pressing "Enter". Once the polygon is graphed, you can manipulate the vertices by dragging them with your mouse or move the entire polygon by dragging a side. After you have placed a polygon you can transform it with a matrix. Enter a transformation matrix at the top left, select a polygon by clicking on it, and press the "Transform!" button to perform the transformation. Pressing the "Monkey!" button at the top left will make a large polygon representing a monkey appear. You can then transform this polygon in the ways described above.


  • You can only drag the red polygons, black polygons are defined by a transformation.
  • When you have selected a polygon (by clicking on it), all of its information is displayed at the lower left. You can edit transformation matrices and preimages interactively here
  • The RESET button will delete all polygons and set the window position to [-10, 10] by [-10, 10]
  • The DELETE SELECTED button will delete the currently selected polygon, if any other polygons were defined with this one as a preimage they will be deleted as well.
  • To manipulate the window you can simply click and drag the grid, to zoom in and out just hold down the SHIFT button while dragging
  • All inputs can accept expressions as input. For example to enter a rotation matrix you can type cos(pi/4) instead of 0.70710... N.B. all angles are in Radians