Test Index

JAMB Mathematics 2021 Paper

Question : 17

Total: 40

Solution:

Concept:

The perimeter of a sector is the sum of its arc length and the two radii.

Explanation:

Arc length is a fraction of the circumference of the circle:

\text{Arc length} = \frac{\theta}{360^\circ} \times 2\pi r

Substitute

\theta = 48^\circ

r = 10.5\text{ cm}

, and

\pi = \frac{22}{7}

\text{Arc length} = \frac{48}{360} \times 2 \times \frac{22}{7} \times 10.5

\text{Arc length} = \frac{48}{360} \times 66 = 8.8\text{ cm}

Now add the two radii to find the perimeter:

\text{Perimeter} = \text{Arc length} + 2r

\text{Perimeter} = 8.8 + 2(10.5) = 8.8 + 21

\text{Perimeter} = 29.8\text{ cm}

Answer:

The perimeter of the sector is

29.8\text{ cm}

The correct option is D.

Go to Question:

Prev Question

Next Question