Area of a Rectangle
Given a rectangle of width W and length L, its area can be calculated as:
[tex]A=W\cdot L[/tex]
If we cut the rectangle by its diagonal, we get to congruent triangles, each one with half the area of the rectangle, that is:
[tex]A_t=\frac{A}{2}_{}[/tex]
The shaded region corresponds to one of these triangles, thus the unshaded region must have the same area as the shaded region.
Area of the shaded region: 42 ft2
Area of the unshaded region: 42 ft2
Area of the rectangle: 84 ft2
