The radius of a circle is increased by 10%, then the area is increased by what percent?
সমাধান
সঠিক উত্তর: Option C
Area of circle A = π*r2
Increase r by 10% new area is: π*(1.1r)2 = 1.21*π*r2
thus area is increased by (1 - 1.21)
= 0.21
= (0.21*100)%
= 21%
