Shearing as an Area-Preserving Transformation

Shearing Parallelograms
Use the applet/figure below to form an argument/proof for why shearing does not change the area of a parallelogram.
Triangle Area
Use the app/figure below to form an argument/proof for why the area of a triangle does not change when a vertex is translated along a line parallel to the opposite side.
– Andy Norton

Information: Shearing as an Area-Preserving Transformation