It is easy to find that the area of this triangle is the root number 3*a? /4, so we can find that the area enclosed by arc AC and line segment AC is a? π/6-3*a? /4, and because it is said that every small arc in the figure is equal, the area of ACF connection is a? π/ 12, so 2x+y=a? π/2-a? =2*(a? π/6-3*a? /4)+a? π/ 12+x, the above two equations can get the value of y, y=( 1+π/3- radical number 3)a? . The first two buildings are idiots. Don't listen to them. This must be right!