Question 26
The figure below shows a quadrilateral ABCD on the xy-plane, where A(a,a -10), B(10,0) and C(0,5). The line AB is parallel to the line CD, and the line AD is perpendicular to CD. Given that a is a positive integer greater than 10, find the smallest value of a such that the area of the quadrilateral ABCD is greater than 200.
