Question

In ΔABC, AB = 16 in, BC = 9 in, AC = 10 in. AD is perpendicular to the extension of BC . Find CD.

Answer 1

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