How it works
Cut a shape into rectangles and triangles you know. Add the areas of the pieces.
A rectangle's area is base times height. A triangle's area is half of base times height.
Check that the pieces don't overlap and leave no gaps.
Worked examples
A house
- A house shape has a 7 by 3 body and a triangle roof with base 7 and height 4.
- Body: 7 × 3 = 21. Roof: 7 × 4 ÷ 2 = 14.
- Add: 21 + 14 = 35 square units.
An L shape
- Cut an L into an 8 by 3 rectangle and a 4 by 2 rectangle.
- 8 × 3 = 24 and 4 × 2 = 8.
- Add: 24 + 8 = 32 square units.
A trapezoid
- Cut a trapezoid into a rectangle 6 by 4 and a triangle with base 2 and height 4.
- 6 × 4 = 24 and 2 × 4 ÷ 2 = 4.
- Add: 24 + 4 = 28 square units.
A taste of the worksheet
These are the first problems of set A. The printable sheet has many more, with an answer key.
- The L-shape is cut into two rectangles by the line inside it. What is the area of the bottom piece in square units? ___
- What is the area of the top piece in square units? ___
- What is the area of the whole L-shape in square units? ___