Answer:
Hence the length of the altitude is:

Explanation:
Right Triangle Altitude Theorem Part a: The measure of the altitude drawn from the vertex of the right angle of a right triangle to its hypotenuse is the geometric mean between the measures of the two segments of the hypotenuse.
In terms of our triangle i.e. figure attached to the answer, this theorem simply states :

Here in our question we are given:
CD=6 and DB=9
Hence the length of the altitude is:
