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JAMB Mathematics 2018 Paper

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Question : 13

Total: 62

An arc of a circle of radius 14cm subtends angle 300° at the centre. Find the perimeter of the sector formed by the arc (take π =

\frac{22}{7}

)

14.67cm
73.33 cm
101.33cm
513.33cm

Solution:

Concept:

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

Explanation:

Given:

r = 14

cm,

\theta = 300^\circ

, and

\pi = \frac{22}{7}

.

Arc length

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

= \frac{300}{360} \times 2 \times \frac{22}{7} \times 14

= \frac{5}{6} \times 88

= \frac{220}{3} = 73.33

cm

Perimeter of the sector

=

arc length

+ 2r

= 73.33 + 2(14)

= 73.33 + 28 = 101.33

cm

Answer:

C. 101.33 cm

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