Discover
Cut a triangle off one end of a parallelogram and slide it to the other end. What shape do you get?
- A rectangle with the same base and height
- A rectangle as long as the slanted side
Key idea
Area of a parallelogram.
Area of a parallelogram , where is a base and the matching height: the distance from the base to the opposite side, measured at a right angle.
Worked example
Base 8 cm, height 5 cm, slanted side 6 cm.
The slanted side is not used.
cm²
Multiply.
Your turn, guided
Your turn: base 7, height 4. The area.
7 · 4.
Practice ★
- A parallelogram has a base of 11 cm, a height of 5 cm and slanted sides of 7 cm. What is its area (cm²)?
- A parallelogram has a base of 3 cm, a height of 7 cm and slanted sides of 8 cm. What is its area (cm²)?
- A parallelogram has a base of 9 cm. Which length is its height?
- The distance between the base and the opposite side, measured at a right angle
- The length of a slanted side
- The longest side
Watch out!
Practice ★★
- A parallelogram has an area of 27 cm² and a base of 3 cm. What is its height (cm)?
- A parallelogram has an area of 32 cm² and a base of 4 cm. What is its height (cm)?
Exit ticket
Three questions to check you have got it.
- A parallelogram has a base of 11 cm, a height of 5 cm and slanted sides of 7 cm. What is its area (cm²)?
- A parallelogram has a base of 3 cm, a height of 7 cm and slanted sides of 8 cm. What is its area (cm²)?
- A parallelogram has a base of 14 cm, a height of 8 cm and slanted sides of 12 cm. What is its area (cm²)?
Summary card
Area of parallelograms
, with the height at a right angle to the base.
Watch out: the slanted side is not the height.