Answer:
Your answer is 4.17
1) Draw the figure; make sure angle C is obtuse.
(2) There are two right triangles -- ADC and ADB.
(3) Let CD=x and AD=y; use the Pythagorean Theorem to form two equations in x and y.
4) Solve the pair of equations. The x^2 and y^2 terms cancel, leaving you with a linear equation in x which is easily solved to find the answer.
So, The length of CD will be 25/6 = 4.17
