Question

on increasing the diameter of circle by 40%, its area increases by?​

Answer 1

Answer:

Hey there

Let the diameter be d and radius be r,

On increasing diameter by 40%,

D = d + 40d/100

D = d + 2d/5

D = (5d + 2d)/5

D = 7d/5

R = 7d/10

Old area = πr^2

= π×d^2/4 ..........(1)

New area = πr^2

= π×49d^2/100 .............(2)

Now,

percentage increased be x,

π×d^2/4 + π×d^2/4 × x/100 = π×49d^2/100

πd^2/4 (1 + x/100) = πd^2/4 (49/25)

1 + x/100 = 49/25

100 + x = 49 × 4

x = 196 - 100

x = 96%

Hope it helps you

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