A parallelogram can be cut and moved to make a rectangle with the same base and height. So its area is base × height. The height must be perpendicular to the base, not the slanted side.
A triangle is half of a parallelogram with the same base and height. So the area of a triangle is ½ × base × height. A triangle with base 6 cm and height 12 cm has area ½ × 6 × 12 = 36 cm².
Worked example
A parallelogram has a base of 11 cm and a perpendicular height of 9 cm. Find its area.
- Area = base × height.
- 11 × 9 = 99.
Answer:99 cm²
Key words
- base
- the side the shape stands on
- perpendicular height
- the height at a right angle to the base
- ½
- one half
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Common Core-referenced: 6.G.A.1