The length of minute hand of a clock is 15 cm. If the minute hand moves for 20 minutes on a circular dial of a clock, the area covered by it is ...... cm². (???? = 3.14).select a proper option (a), (b), (c) or (d) from given options so that the statement becomes correct.
(a) 235.5
(b) 471
(c) 141.3
(d) 706.5
Answers
Answered by
2
a. 235.5 is the right answer
Answered by
8
Solution :
Radius of the sector ( r ) = length of
minutes hand
r = 15 cm
Sector angle ( x ) = angle made at the
center in 20 minutes
= 6° × 20
= 120°
Sector area ( A ) = ( x/360)×πr²
= ( 120/360 ) × 3.14 × 15²
= ( 1/3 ) × 3.14 × 15 × 15
= 3.14 × 5 × 15
= 235.5 cm²
Therefore ,
Option ( a ) is correct.
••••
Radius of the sector ( r ) = length of
minutes hand
r = 15 cm
Sector angle ( x ) = angle made at the
center in 20 minutes
= 6° × 20
= 120°
Sector area ( A ) = ( x/360)×πr²
= ( 120/360 ) × 3.14 × 15²
= ( 1/3 ) × 3.14 × 15 × 15
= 3.14 × 5 × 15
= 235.5 cm²
Therefore ,
Option ( a ) is correct.
••••
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