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]

  • A 5.2cm
  • B 10.5cm
  • C 13.2cm
  • D 20.6cm
  • E 31.4cm
waec 1990mathematics

The correct answer is B. 10.5cm

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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