Why does the formula A = work for triangles other than right triangles? To answer this question, let's look at parallelograms, since we'll derive the triangle formula from the formula for the area of a parallelogram.
Explain how the area of a parallelogram with height a and base b (as shown below) is found using the formula A = a b. How does it compare to the area of a rectangle with the same height and base?
Examine the figure below, in which two congruent triangles are placed together to form a parallelogram. Using this figure, explain how the formula for the area of a triangle relates to the formula for the area of a parallelogram.
Note the height of the triangle, h, is the length of the line segment perpendicular to the base and adjoining it to the opposite vertex. This is equal to the height of the parallelogram. Close Tip