2009 AMC 10B Problem 10

Attempt Problem 10 of the 2009 AMC 10B below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2009 AMC 10B solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

10.

A flagpole is originally 55 meters tall. A hurricane snaps the flagpole at a point xx meters above the ground so that the upper part, still attached to the stump, touches the ground 11 meter away from the base. What is x?x?

2.02.0

2.12.1

2.22.2

2.32.3

2.42.4

Answer: E
Concepts:Pythagorean Theoremright triangle
Difficulty rating: 1140
Solution:

The standing stump has height x,x, and the snapped piece of length 5x5-x is the hypotenuse of a right triangle with legs xx and 1.1. By the Pythagorean Theorem, x2+12=(5x)2=x210x+25, \begin{aligned} x^2+1^2 &= (5-x)^2 \\ &= x^2-10x+25, \end{aligned} so 10x=2410x=24 and x=2.4.x=2.4.

Thus, the correct answer is E.

← Problem 9#9
Full Exam

Problem 10 in Other Years