Area of a Parallelogram - Co-ordinate Geometry

Investigate how to find the area of a parallelogram (with vertex at (0,0)). Click 'Show CD' in order to show the line through C and D, as well as E, its point of intersection with the y-axis. Click 'Show ABFE' (and unclick 'Show ABCD' and 'Show CD') to show the new parallelogram with the vertices A, B, E and new vertex F. Click 'Show Areas' and compare the areas of both parallelograms. Why do you think the areas are like this?# Click 'Show Dimensions' to show the dimensions needed to find the area of parallelogram ABFE.