The length of the minute of a watch is 42 mm. The area swept by it in 30 minutes (in $$mm^2$$) by taking π as 3.14 is:-
60 minutes = 360 degrees or 2$$\pi$$ radians.
$$\Rightarrow$$ 1 minute = 60 degrees.
$$\Rightarrow$$ 30 minutes = 180 degrees or $$\pi$$ radians.
Therefore area (A) swept by minute hand of length 42 mm in 30 minutes = area of semi-circle of radius (r = 42 mm) .
$$\Rightarrow A = \pi r^2\div 2 = 3.14\times 42^2\div 2 = 2769.5 mm^2$$.
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