RRB NTPC 18 January 2017 Paper

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Question : 71 of 120

Marks: +1, -0

Find the increase in circumference of a circle of radius 14 cm, if the radius is increased by 7 cm. (π = $22 /7$ )

44 cm
22 cm
66 cm
88 cm

Solution:

when

{ R } _ { 1 }

= 14 cm,

{ C } _ { 1 }

= 2π

{ R } _ { 1 }

\ { R } _ { 2 } = 21 \ { cm } , \ { C } _ { 2 } = 2 π{ R } _ { 2 }

\ { C } _ { 2 } - { C } _ { 1 } = 2π { R } _ { 2 } - 2 \π \ { R } _ { 1 }

=

2π[ { R } _ { 2 } - { R } _ { 1 }]

=2π[21-14]
=2×

22/7

×7=44cm

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