Investigate the relationship between the area of a triangle and the area of a rectangle
with the same height and base.
About the activity
Manipulate the vertices to make a triangle of any desired shape.
See that whatever shape is chosen, by appropriately subdividing the resulting triangle, the shaded
smaller triangles can be dragged to fill exactly half the area of the surrounding rectangle.
(Take careful note of the piece shaded black when the midpoint of the longest side is outside the
The side lengths and angle sizes can be displayed as well, allowing
validation of the formulas for the area: A= ½bh, A = ½ab sin C and Heron's formula.