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5. If the radius of a circle is increased by 20% then the area is increased by :
A. 44%
B. 120%
C. 144%
D. 40%
None of the above​

Respuesta :

alinateow
example :
radius of the circle ( before ) = 10cm
radius of circle ( after )
100% = 10
120% = 12

area of circle before = pi x 10 square = 314.15

area of circle after = pi x 12 square = 452.38

percentage increased
= area of circle ( after ) - area of circle ( before ) divides by area of circle (before) x 100%

= 44%

Answer : A

(Sorry if it’s wrong , I tried my best )

Answer:

A. 44 %

Step-by-step explanation:

Suppose Area of a circle is A=πr^2                     (1)

When radius increase by 20%

r'=r + 20/100 r = 1.2 r

Now area

Area = πr'^2

        = π (1.2 r)^2

        = 1.44πr^2                                                     (2)

Difference between the area (1) and (2)

        =1.44πr^2-πr^2

        = .44πr^2

Taking percentage

       =.44πr^2*100/πr^2

       =44%

Hence 44% is answer.

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