Question

the minute hand of a clock is 21 cm long calculate the area swept by it and the distance travelled by it in 20 minutes​

Answer 1

Step-by-step explanation:

We know that minte hand is just the radius of circle.

Area covered 1/3 of circle.

area of circle =2πr^2=2×22/7×(21cm) ^2=2×22/7×441=2×63=126cm^2.

Answer 2

The area covered by minute hand in 20 minutes is 462 cm²

Step-by-step explanation:

Given: Length of minute hand = 21 cm

To find: Area swept by it in 20 minutes

Angle formed by  minute hand of a watch is given by  

$\theta=\dfrac{\text { Total angle of circle in 1 hour}}{\text {Minutes in 1 hour } }$

Now angle formed in 20 minutes is given by

$\theta = \dfrac{360}{60} \times 20 = 120 ^\circ$

radius r= 21 cm

area of sector is $area= \pi r^2 \dfrac{\theta}{360^\circ}$

Therefore

$area= \dfrac{22}{7} \times 21 \times 21 \times \dfrac{120 ^\circ}{360^ \circ} = 462 cm^2$

The area covered by minute hand in 20 minutes is 462 cm²

#Learn more

A horse is tied with a rope 7 m long to one corner of a square field of side 17 m. Find the area of  grass that the horse can graze.

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