Solids, angles and quadrilaterals · Usually met around P2
Squares and rectangles
Rectangle: opposite sides equal; square: all four.
How to do it
Method
Rectangle: opposite sides equal; square: all four
5 + 3 + 5 + 3 = 16
Another way
Neighbours twice
5 + 3 = 8, 8 + 8 = 16
In full
A rectangle has 4 sides and 4 right angles, and its opposite sides are equal. A square also has 4 right angles, and all 4 of its sides are equal, so a square is a special rectangle. A rectangle whose neighbouring sides are 5 cm and 3 cm has sides 5, 3, 5 and 3. To finish a rectangle or square on squared paper, count the squares: opposite sides must match and every angle must be a right angle. Or add two neighbouring sides and double it: 5 + 3 = 8, 8 + 8 = 16.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
In rectangle ABCD, AB is 15 cm and BC is 11 cm. How long is CD?
Show the answer and working
Answer: 15 cm
CD is opposite AB, and a rectangle's opposite sides are equal: 15 cm.
Example 2
The blue dots on the squared paper are three corners of a rectangle. Which point is the fourth corner?
- A. A
- B. B
- C. C
- D. D
Choose the right answer
Show the answer and working
Answer: B. B
The fourth corner lines up with two of the blue dots: count squares so opposite sides match.
Example 3
A rectangle's neighbouring sides are 16 cm and 15 cm. How long are its four sides added together?
Show the answer and working
Answer: 62 cm
Opposite sides are equal: 16 + 15 + 16 + 15 = 62.
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