Multiple choice

An arc of a circle subtends an angle of 60° at centre. If the radius of the circle is 21 cm, the length of the arc will be ______.

  1. 18 cm

  2. 20 cm

  3. 22 cm

  4. none of these
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C Correct answer
Explanation

The arc length formula is (theta/360) * 2 * pi * r. With theta=60 and r=21, length = (60/360) * 2 * (22/7) * 21 = (1/6) * 2 * 22 * 3 = 22 cm.

AI explanation

Using the arc length formula l = (theta/360) * 2 * pi * r, we substitute the given values to get l = (60/360) * 2 * (22/7) * 21. Simplifying the fraction and multiplying gives l = (1/6) * 2 * 22 * 3, which equals 22 cm. The length of the arc is 22 cm.

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