Question

radius of a circle is increased by 200%, then its area will be increased by:
7. If the radius of ac
(B) 200%
(C) 400%
(D) 800%
(A) 100%​

Answer 1

radius increased by 200%, then its area will be increased

by 800%

Answer 2

The area will be increased by

Given data :

The radius of the new circle increased by 200% than the initial circle.

- Let,the radius of the initial circle = r (assume r as a variable to perform the necessary mathematical calculations)

- So,the area of the initial circle

= π × (radius)²

= πr²

- Increased radius of the new circle

= r × 200/100

= 2r

- Radius of the new circle

= (Initial circle's radius + Increased radius)

= (r+2r)

= 3r

- New circle's area

= π × (3r)²

= 9πr²

- So,the increased area

= New circle's area - Increased circle's area

= 9πr²-πr²

= 8πr²

- So,the percentage of the increased area

= 100× 8πr²/πr²

= 100×8

= 800%

So,the area will be increased by 800% (answer).