the radius of a sphere is increased by 10 % . the surface area increases by ?
since 4 x pi x radius x radius = surface area . therefore , net % change in area = ( x + y + xy / 100 ) % = [ 10 + 10 + ( 10 x 10 ) / 100 ] % or 21 % . answer : a
multiply(divide(subtract(surface_sphere(add(const_1, divide(10, const_100))), surface_sphere(const_1)), surface_sphere(const_1)), const_100)