Home / iGCSE Mathematics (0580) – C5.3 Circles, arcs and sectors- Exam Style Questions Paper 3

iGCSE Mathematics (0580) - C5.3 Circles, arcs and sectors- Exam Style Questions Paper 3- New Syllabus

Question

The diagram shows a garden.
The garden has a circular pond and the shaded area is grass.
The width of the grass area is equal to the diameter of the pond.

(a) Find the area of the pond.

(b) Find the area of the grass.

(c) Find the percentage of the garden that is grass.

Most-appropriate topic codes (Cambridge IGCSE Mathematics 0580):

• C5.3 Circles, arcs and sectors (a,b)
• C5.5 Compound shapes and parts of shapes (b,c)
▶️ Answer/Explanation

(a)
The diameter of the pond is $10\text{ m}$, so the radius is $5\text{ m}$. The total area of the full circular pond is:
$\text{Area} = \pi \times 5^2$
$\text{Area} \approx 78.5\text{ m}^2$
✅ Answer: 78.5

(b)
The diagram implies half of the circular pond intrudes into the rectangle, creating the grass area. First, find the total area of the $10\text{ m}$ by $16\text{ m}$ rectangle, then subtract half the area of the pond.
$\text{Area of rectangle} = 10 \times 16 = 160$
$\text{Grass Area} = 160 – (\frac{1}{2} \times 78.54)$
$\text{Grass Area} = 160 – 39.27 = 120.7\text{ m}^2$
✅ Answer: 120.7

(c)
The total area of the garden is the area of the grass plus the area of the pond inside the garden outline (the rectangle), which is exactly the area of the $10 \times 16$ rectangle.
$\text{Percentage} = (\frac{120.73}{160}) \times 100 \approx 75.5\%$
✅ Answer: 75.5

Question

This shape is made from a rectangle and a semicircle.
The diameter of the semicircle is $10 \text{ cm}$.

Calculate the perimeter of this shape.

Most-appropriate topic codes (Cambridge IGCSE Mathematics 0580):

• C5.3 Circles, arcs and sectors
▶️ Answer/Explanation
The total perimeter is made up of the straight edges forming the base and sides, plus the straight sections on top, plus the curved arc of the semicircle.
The straight top sections equal the total width minus the diameter: $16 \text{ cm} – 10 \text{ cm} = 6 \text{ cm}$ in total.
Calculate the length of the semicircular arc: $\frac{1}{2} \times \pi \times d = \frac{1}{2} \times \pi \times 10 = 5\pi \approx 15.71 \text{ cm}$.
Add all the outer edges together: $16 (\text{base}) + 9 (\text{left}) + 9 (\text{right}) + 6 (\text{top parts}) + 15.71 (\text{arc})$.
$\text{Perimeter} = 40 + 15.71 = 55.71 \text{ cm}$.
✅ Answer: $55.7 \text{ cm}$
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