Key Concepts: Areas of Parallelograms and Triangles

Area of a Parallelogram

A = bh

where b is the base and h is the height (perpendicular to the base).

Area of a Triangle

A = ½bh

where b is the base and h is the corresponding height.

Key Ideas

• The height must be perpendicular to the base — it is not necessarily a side of the figure.
• Any side can be chosen as the base; the height changes accordingly.
• A diagonal divides a parallelogram into two congruent triangles.