objectives: vocabulary: deduce and use formula for the perimeter and area of a rectangle. calculate...
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Objectives:
Vocabulary:
• Deduce and use formula for the perimeter and area of a rectangle.
• Calculate the perimeter and area of shapes made from rectangles.
The area of this rectangle is 12 cm².
What are the possible dimensions – length and width of this rectangle?
Which of the rectangles you have found has the largest perimeter?
Possible answers 1 x 12 cm 2 x 6 cm 3 x 4 cm
(any other answers would involve lengths with decimals).
Largest perimeter 1 x 12 cm rectangle with a perimeter of 26cm.
Even greater perimeters are achieved if decimal lengths are acceptable!!!
( Example 0.1 x 120cm perimeter is 240.2cm.)
This rectangle has a perimeter of 12 cm.
Find as many different rectangles with a perimeter of 12cm.
Which of the rectangles has the largest area?
Possible answers: 4 x 2 cm, 3 x 3 cm, 1 x 5 cm
Any other answers would include decimal lengths.
Largest area: 3 x 3 cm = 9cm²
8cm6c
m
3cm
5cm
Work out the area and perimeter of the shape.
8cm
6cm
3cm
5cm
A
B
Area is:
A + B
Perimeter: 6 + 8 + 3 + 3 + 3 + 5cm
8cm
6cm
Area is: -
Perimeter: Why?
3cm
3cm
Find the area and perimeter of each of the shapes below: (all measurements given in cms)
5 8
9
3
4
4
3
8
5
2
7
2
4
3
10
4
7
5
W/S 9.1B
Answers:
5 8
9
3
4
4
3
8
5
2
7
2
4
3
10
4
7
5
A = 47 cm²
P = 34 cm
A = 40 cm²
P = 30 cm
A = 32 cm²
P = 32 cm
A = 75 cm²
P = 38 cm
15m
10m
3m
3m
Calculate the area shaded green.
Working:
(15 x 10) – (3 x 3) = 150 – 9 = 141m²
60cm
40cm
10cm
10cm
Calculate the area of the blue cross.
Working:
(10 x 60) + (10 x 40) – (10 x 10)
600 + 400 - 100 = 900cm²
W/S 9.2B
Objectives:
Vocabulary:
• Deduce and use formula for the perimeter and area of a rectangle.
• Calculate the perimeter and area of shapes made from rectangles.
Thank you for your attention