Area & Perimeter of 2-D Shapes (Grade 9) — Worksheet & Memo

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Grade 9 · Area and Perimeter of 2D Shapes

Area & Perimeter of 2-D Shapes (Grade 9)

MEMORANDUM

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Class:

Date:

Mark

/ 25

Answer all questions. Show all your working — marks are awarded for method as well as the final answer. Teacher copy: accept any correct equivalent method.

1
A square has an area of 225 cm². Determine the length of one side, and hence its perimeter.
(3)
side = √225 = 15 cm (2)
Perimeter = 4 × 15 = 60 cm (1)✓✓✓ (3)
2
Area of a rectangle 9 cm by 6 cm.
(1)
54 cm²✓ (1)
3
Perimeter of a rectangle 9 cm by 6 cm.
(2)
2(9 + 6) = 30 cm✓✓ (2)
4
Area of a triangle, base 12 cm, height 7 cm.
(2)
½ × 12 × 7 = 42 cm²✓✓ (2)
5
Area of a parallelogram, base 9 cm, height 5 cm.
(2)
45 cm²✓✓ (2)
6
Area of a trapezium, parallel sides 8 cm and 12 cm, height 5 cm.
(3)
½(20) × 5 = 50 cm²✓✓✓ (3)
7
Area of a circle with radius 7 cm (π ≈ 3,14).
(2)
3,14 × 49 = 153,86 cm²✓✓ (2)
8
Circumference of a circle with radius 7 cm (π ≈ 3,14).
(2)
2 × 3,14 × 7 = 43,96 cm✓✓ (2)
9
Area of a circle with diameter 10 cm (π ≈ 3,14).
(3)
r = 5 → 3,14 × 25 = 78,5 cm²✓✓✓ (3)
10
A 10 × 8 rectangle has a 3 × 2 piece cut out. Find the remaining area.
(3)
80 − 6 = 74 cm²✓✓✓ (3)
11
A shape is enlarged by scale factor 3. What happens to its area?
(2)
It becomes 9 times bigger (3²).✓✓ (2)

TOTAL: 25 marks