Difference between revisions of "2015 AMC 10A Problems/Problem 11"
m (→Solution) |
|||
Line 1: | Line 1: | ||
+ | {{duplicate|[[2015 AMC 12A Problems|2015 AMC 12A #8]] and [[2015 AMC 10A Problems|2015 AMC 10A #11]]}} | ||
==Problem 11== | ==Problem 11== | ||
Line 7: | Line 8: | ||
==Solution== | ==Solution== | ||
Let the rectangle have length <math>4x</math> and width <math>3x</math>. Then by 3-4-5 triangles (or the Pythagorean Theorem), we have <math>d = 5x</math>, and so <math>d = \dfrac{x}{5}</math>. Hence, the area of the rectangle is <math>3x \cdot 4x = 12x^2 = \dfrac{12d^2}{25}</math>, so the answer is <math>\boxed{\textbf{(C) }\frac{12}{25}}</math> | Let the rectangle have length <math>4x</math> and width <math>3x</math>. Then by 3-4-5 triangles (or the Pythagorean Theorem), we have <math>d = 5x</math>, and so <math>d = \dfrac{x}{5}</math>. Hence, the area of the rectangle is <math>3x \cdot 4x = 12x^2 = \dfrac{12d^2}{25}</math>, so the answer is <math>\boxed{\textbf{(C) }\frac{12}{25}}</math> | ||
+ | |||
+ | == See also == | ||
+ | {{AMC10 box|year=2015|ab=A|num-b=10|num-a=12}} | ||
+ | {{AMC12 box|year=2015|ab=A|num-b=7|num-a=9}} |
Revision as of 20:47, 4 February 2015
- The following problem is from both the 2015 AMC 12A #8 and 2015 AMC 10A #11, so both problems redirect to this page.
Problem 11
The ratio of the length to the width of a rectangle is : . If the rectangle has diagonal of length , then the area may be expressed as for some constant . What is ?
$\textbf{(A)}\ \frac{2}{7}\qquad\textbf{(B)}\ \frac{3}{7}\qquad\textbf{(C)}\ \frac{12}{25}\qquad\textbf{(D)}}\ \frac{16}{25}\qquad\textbf{(E)}\ \frac{3}{4}$ (Error compiling LaTeX. ! Extra }, or forgotten $.)
Solution
Let the rectangle have length and width . Then by 3-4-5 triangles (or the Pythagorean Theorem), we have , and so . Hence, the area of the rectangle is , so the answer is
See also
2015 AMC 10A (Problems • Answer Key • Resources) | ||
Preceded by Problem 10 |
Followed by Problem 12 | |
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 | ||
All AMC 10 Problems and Solutions |
2015 AMC 12A (Problems • Answer Key • Resources) | |
Preceded by Problem 7 |
Followed by Problem 9 |
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 | |
All AMC 12 Problems and Solutions |