Question:
The large hand of a clock Is 42 cm long. How many centimetres does its extremity move in 20 minutes?
Solution:
For 20 minutes $=\theta=4 \times 30^{\circ}=120^{\circ}$
We know that l = r × θ
$\mathrm{I}=42 \times 120 \times \frac{\pi}{180}=28 \times \frac{22}{7}=88$
Therefore, the length is equal to 88 cm.
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