If each side of a right triangle is increased by 10% and the base(b) is half of the height, find the percentage change in its area? Choose the correct choice from the following options
A) 26 %  B) 21 %  C) 15 %  D) 18 %  E) 12 %

Rationale: a = 1 / 2 x b x h or 1 / 2 x 2 a x a ( for simplification ) new h = 220 a / 100 = 22 a / 10 new b = ( 110 a x 100 ) = = 11 a / 10 new area = 1 / 2 ( 22 a x 11 a ) / ( 10 x 10 ) = ( 121 a ² / 100 ) increased area = = ( 121 a ² / 100 ) - a ² increase % = [ ( 21 a ² / 100 ) x ( 1 / a ² ) x 100 ] % = 21 % answer : b
Answer: B