If all the sides of a right triangle increase in length by 10%, then by what percentage does the area of the triangle increase?
Choices
A) 21%  B) 42%  C) 80%  D) 96%  E) 120%
Let B be the base and H be the height of the original triangle.   The original area is (1/2)BH.   The area of the expanded triangle is (1/2)(1.1B)(1.1H) = (1.1)(1.1)(1/2)BH = 1.21(1/2)BH   The answer is 21%.
<result>A</result>
If all the sides of a right triangle increase in length by 10%, then by what percentage does the area of the triangle increase?