It is given that line segment BC is congruent to line segment EC and that line segment AC is congruent to DC. Because of the vertical angles theorem, angle BCA is equal to angle DCE. Therefore, triangles CBA AND DEC are congruent by SAS. Using CPCTC, BA is equal to ED.
8/18 because just times them by 2 and it will be 8/28.
The diameter of the circle is needed. But to solve, you would simply multiply the diameter of the circle by pi (3.14).