Question

if the radius of a circle is increased by 10% by what percent will its area increase?​

Answer 1

Answer:

21%

Step-by-step explanation:

I am answering after a long time so might be difficult to type but anyways.
So first of all its given that radius is increased by 10%
meaning +10%
now we are gonna take radius as r.
area of circle = pir^2 .
as radius is increased by 10% therefore
10% of r = 0.1
r+0.1r = 1.1r.
now as area is in radius square hence 1.1x1.1 = 1.21.
now original r was 1. therefore 1.21-1 = 0.21 = 21/100 = 21%.

Answer 2

Answer:

21%

Step-by-step explanation

By successive formula,

x+x+(x+x)/100

(10)+(10)+(10*10)/100

20+1=21%

(This is a shortcut method, can use for mcqs and short answers , the real explained answer is already given by someone :))