SAT math question help

Test Preparation
1

<p>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</p>

<p>A. 4 feet
B. 5 feet
C. 6 feet
D. 7 feet
E. 8 feet</p>

<p>Can someone explain this to me? I read the explanation and I still don't get it.</p>

2

<p>it's a right triangle</p>

<p>hypotenuse = 25 feet
leg 1 = 7 feet</p>

<p>using the Pythagorean theorem the other leg = 24 feet</p>

<p>24 - 4 = 20</p>

<p>25^2 - 20^2 = 225</p>

<p>square root of 225 = 15</p>

<p>15-7 = 8</p>

<p>So the answer is E</p>