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WAEC Mathematics 2017 Paper

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Question : 13

Total: 49

An arc of a circle of radius 7.5cm is 7.5cm long. Find, correct to the nearest degree, the angle which the arc subtends at the centre of the circle. [Take

\pi = \frac{22}{7}

]

29 $^{\circ}$
57 $^{\circ}$
65 $^{\circ}$
115 $^{\circ}$

Solution:

lac = $\frac{\theta}{360}$ x 2 $\pi$ r

7.5 = $\frac{\theta}{360}$ x 2 x $\frac{22}{7}$ x 7.5

7.5 = $\frac{330\theta}{2520}$

$\theta$ = $\frac{7.5}{0.1309}$

$\theta$ = 57.29

$\theta$ = 57 $^{\circ}$

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