The minute hand of a clock is 15 cm long
Angle described by the minute hand in 60 minutes = 360°
Angle described by minute hand in 20 minutes = 360/60 x 20 = 120°
So, area swept by it in 20 minutes = Area of the sector having central angle 120° and radius 15 cm
= θ/360 (πr2)
= 120/360 x 22/7 x 15 x 15
= 235.5
Therefore, the area swept by minute hand in 20 minutes is 235.5 cm2.