Final answer:
Using the Pythagorean theorem, we can find that the length of DC is 6 units.
Step-by-step explanation:
To find the length of DC in right triangle ABC with altitude BD drawn to hypotenuse AC, we can use the Pythagorean theorem. In our triangle, AD and BD are the legs, and AC will be the hypotenuse. Since we are given that AD = 9 and BD = 12, we can set up an equation as follows:
AD² + BD² = AC²
9² + 12² = AC²
81 + 144 = AC²
225 = AC²
AC = √225
AC = 15
Now, to find DC, we subtract the length of AD from AC:
DC = AC - AD
DC = 15 - 9
DC = 6
Thus, the length of DC is 6 units.