Areas

Parallelogram

Use the known facts about angles, congruent triangles and the area of a rectangle to show that the area of a parallelogram is bh where b is the base (one of the side lengths) and h is the height perpendicular to the base b.

Triangle

Show that the area of a triangle is bh/2 where b is the base (one of the side lengths) and h is the perpendicular height to the base b.

Extra exercise, another version of the triangle area

Show that the area is bh/2 even if you move the points!