Question

The minute hand of a watch is

21 cm long. What area will be

covered by it in 20 minutes?​

Answer 1

Answer:

area of sector = ∅/360 πr²

Step-by-step explanation:

so, radius = 21 cm

angle = (360°/60°)×20=120°    (as each minute makes an angle of 360/60)...

now using the formula,

120/360×22/7×21²

66cm

Answer 2

The area would be 462 cm²

Step-by-step explanation:

Given,

The length of minute hand, r = 21 cm,

Time = 20 minutes,

∵ 60 minutes = 360°,

⇒ 1 minute = $\frac{360}{60}$ = 6°

⇒ 20 minutes = 20 × degrees in 1 minutes = 20 × 6° = 120°

Thus, angle made by minute hand in 20 minutes, $\theta$ = 120°

Hence, the area covered in 20 minutes,

$A=\frac{\theta}{360^{\circ}} \pi r^2$

$=\frac{120^{\circ}}{360^{\circ}}\pi 21^2$

$=\frac{1}{3}\times \frac{22}{7}\times 21\times 21$

$=22\times 21$

= 462 cm²

#Learn more:

A minute hand of watch is 3cm.after 40minute how distance traveled the tip of minute hand of watch

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