WAEC - Mathematics (1990 - No. 18)
In the diagram above, O is the center of the circle with radius 10cm, and ∠ABC = 30°. Calculate, correct to 1 decimal place, the length of arc AC [Take π = 22/7]
5.2cm
10.5cm
13.2cm
20.6cm
31.4cm
Explanation
In the figure, < AOC = 2 x < ABC = 60° (angle subtended at the centre)
\(\therefore\) Arc AC = \(\frac{60}{360} \times 2 \times 10 \times 3.14\)
= \(\frac{31.4}{3}\)
= 10.466 cm \(\approxeq\) 10.5 cm
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