what will be the increase in area of circle if its radius is increased by 40%???????
Area (A1) of circle with radius r is
= pai. r^2
when radius increase by 40%, that means new radius become,
= [r + 40% * r]
= [ r + (40/100)* r ]
= [ r +(2/5)*r]
= (7/5) *r or, (7r)/5
now Area of circle with radius (7/5)*r is,
A2= pai* [(7/5)*r] ^2 or, pai* [(49/25)*r^2]
now increase in Area of circle is A2 - A1 , = [pai* (49/25) * r^2 ] - [pai* r^2]
= (24/25) * pai* r^2 = (24/25) *A1, so the Area of the circle is increased by 96 %