My post of The importance of visualization elicited the following response:

Hi Scott Sheppard,

[email protected] has left you a comment:

The correct answer is **4 feet**. It's a trick question. Has nothing to do with Pythagorean theorem. You have a fixed length object and a 90-degree angle. Everything else is irrelevant info thrown in to confuse. Draw it up in AutoCAD :)

For those who didn't see the question in my original post:

*A 25-foot ladder is placed against a vertical wall of a building, with the bottom of the ladder standing on concrete 7 feet from the base of the building. If the top of the ladder slips down 4 feet, then the bottom of the ladder will slide out how many feet? *

According The Official SAT Question of the Day site, my answer of 8 feet was correct:

*The ladder, the wall, and the ground form a right triangle with a 25-foot hypotenuse. At first, the bottom of the ladder is 7 feet from the base of the building, so one leg of the right triangle measures 7 feet; the length of the other leg, x, can be found by solving 7 ^{2} + x^{2} = 252, which is the Pythagorean theorem. From this, you can figure out that the other leg measures 24 feet.*

*After the ladder slips down 4 feet, the 24-foot leg of the right triangle becomes 20 feet long. The other leg then has to be 15 feet long. This length is found by solving 202 + y ^{2} = 252, which is again the Pythagorean theorem.*

*Since the distance between the bottom of the ladder and the base of the building increases from 7 feet to 15 feet, the amount that the bottom of the ladder slides out is 8 feet. *

Despite the fact that my original answer was correct using the Pythagorean theorem, I liked [email protected]'s suggestion of drawing it up in AutoCAD.

Thanks to **Heidi Hewett** for the tip regarding setting my dynamic input to use absolute coordinates.

Using design applications to check the math is alive in the lab.