A rectangular stained glass window is made up of identical triangular parts as pictured below.
36 inches
48 inches
What is the area of the shaded triangular section?
Note that the width of each rectangle = 48 / 3 = 16 in
And the height of each rectangle = 36 / 4 = 9 in
So.....the area of each of these rectangles = 16 * 9 = 144 in^2
And the shaded area is 1/2 of this = 72 in^2
The entire window is 48 x 36 = 1728 in2
made up of 24 triangles each triangle (which is shaded region) = 1728/24 = 72 in^2