Area of Triangles & Parallelograms
Calculate the area of parallelograms and triangles using formulae (A = b × h for parallelograms, A = ½ × b × h for triangles)
What a learner can do afterwards
- Calculate the area of a parallelogram with base 8 cm and height 5 cm
- Calculate the area of a triangle with base 12 cm and height 7 cm
- Explain why the area of a triangle is half the area of a related parallelogram
1 · Read
Area tells you how much flat space a shape covers. You measure it in square units, like square centimetres (cm²). For a parallelogram, the formula is simple: multiply the base by the height. A = b × h.
A parallelogram has a base of 8 cm and a height of 5 cm. Multiply the base by the height: 8 × 5 = 40. The area is 40 cm².
A triangle is different. Two matching triangles fit together to make a parallelogram with the same base and height. So a triangle's area is always half of that parallelogram's area. The formula is A = ½ × b × h.
Always multiply base by height first. Only halve the answer if you are working with a triangle. Keep the units as square centimetres (cm²).
Multiply base by height for a parallelogram; halve that answer for a triangle.
2 · Watch
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Where it sits
Where this leads
18 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.