Question

In right triangle ABC below, CD is the altitude to hypotenuse AB. If CD=6 and the ratio of AD to AB is 1:5, determine and state the length of BD.

Answer 1

Explanation:

the altitude makes a right angle at hypotenuse

cd^2+ ad^2 = ac^2

36+ (h/5)^2 = ac^2

ad/ab = 1/5; ad/h = 1/5; ad=h/5

similarly

bd^2+cd^2 = bc^2

(4/5)^2+ 36 = bc^2

ac^2+bc^2 = ab^2

36+h^2/25+ 16/25h^2+36 = h^2

h= 15

bd/ab = 4/5

bd= .8*15=12