Difference between revisions of "1992 AIME Problems/Problem 11"

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== Problem ==
 
== Problem ==
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Lines <math>l_1^{}</math> and <math>l_2^{}</math> both pass through the origin and make first-quadrant angles of <math>\frac{\pi}{70}</math> and <math>\frac{\pi}{54}</math> radians, respectively, with the positive x-axis. For any line <math>l^{}_{}</math>, the transformation <math>R(l)^{}_{}</math> produces another line as follows: <math>l^{}_{}</math> is reflected in <math>l_1^{}</math>, and the resulting line is reflected in <math>l_2^{}</math>. Let <math>R^{(1)}(l)=R(l)^{}_{}</math> and <math>R^{(n)}(l)^{}_{}=R\left(R^{(n-1)}(l)\right)</math>. Given that <math>l^{}_{}</math> is the line <math>y=\frac{19}{92}x^{}_{}</math>, find the smallest positive integer <math>m^{}_{}</math> for which <math>R^{(m)}(l)=l^{}_{}</math>.
  
 
== Solution ==
 
== Solution ==

Revision as of 22:37, 10 March 2007

Problem

Lines $l_1^{}$ and $l_2^{}$ both pass through the origin and make first-quadrant angles of $\frac{\pi}{70}$ and $\frac{\pi}{54}$ radians, respectively, with the positive x-axis. For any line $l^{}_{}$, the transformation $R(l)^{}_{}$ produces another line as follows: $l^{}_{}$ is reflected in $l_1^{}$, and the resulting line is reflected in $l_2^{}$. Let $R^{(1)}(l)=R(l)^{}_{}$ and $R^{(n)}(l)^{}_{}=R\left(R^{(n-1)}(l)\right)$. Given that $l^{}_{}$ is the line $y=\frac{19}{92}x^{}_{}$, find the smallest positive integer $m^{}_{}$ for which $R^{(m)}(l)=l^{}_{}$.

Solution

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See also