Difference between revisions of "1965 AHSME Problems/Problem 36"

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== Solution ==
 
== Solution ==
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<asy>
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import geometry;
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point O=(0,0);
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point A=(10,10);
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point B=(10,0);
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point C;
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line OA=line(O,A);
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line OB=line(O,B);
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// Lines OA and OB
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draw(OA);
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draw(OB);
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// Points O, A, and B
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dot(O);
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label("O",O,S);
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dot(A);
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label("A",A,NW);
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dot(B);
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label("B",B,S);
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// Segments AB and BC
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draw(A--B);
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pair[] x=intersectionpoints(perpendicular(B,OA),(O--A));
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C=x[0];
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dot(C);
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label("C", C, NW);
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draw(B--C);
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// Right Angle Markers
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markscalefactor=0.1;
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draw(rightanglemark(O,B,A));
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draw(rightanglemark(B,C,O));
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// Length Labels
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label("$a$", midpoint(A--B), E);
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label("$b$", midpoint(B--C), NE);
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</asy>
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<math>\fbox{E}</math>
 
<math>\fbox{E}</math>
  

Revision as of 18:26, 19 July 2024

Problem

Given distinct straight lines $OA$ and $OB$. From a point in $OA$ a perpendicular is drawn to $OB$; from the foot of this perpendicular a line is drawn perpendicular to $OA$. From the foot of this second perpendicular a line is drawn perpendicular to $OB$; and so on indefinitely. The lengths of the first and second perpendiculars are $a$ and $b$, respectively. Then the sum of the lengths of the perpendiculars approaches a limit as the number of perpendiculars grows beyond all bounds. This limit is:

$\textbf{(A)}\ \frac {b}{a - b} \qquad  \textbf{(B) }\ \frac {a}{a - b} \qquad  \textbf{(C) }\ \frac {ab}{a - b} \qquad  \textbf{(D) }\ \frac{b^2}{a-b}\qquad \textbf{(E) }\ \frac{a^2}{a-b}$

Solution

[asy]  import geometry; point O=(0,0); point A=(10,10); point B=(10,0); point C; line OA=line(O,A); line OB=line(O,B);  // Lines OA and OB draw(OA); draw(OB);  // Points O, A, and B dot(O); label("O",O,S); dot(A); label("A",A,NW); dot(B); label("B",B,S);  // Segments AB and BC draw(A--B); pair[] x=intersectionpoints(perpendicular(B,OA),(O--A)); C=x[0]; dot(C); label("C", C, NW); draw(B--C);  // Right Angle Markers markscalefactor=0.1; draw(rightanglemark(O,B,A)); draw(rightanglemark(B,C,O));  // Length Labels label("$a$", midpoint(A--B), E); label("$b$", midpoint(B--C), NE);  [/asy]

$\fbox{E}$

See Also

1965 AHSC (ProblemsAnswer KeyResources)
Preceded by
Problem 35
Followed by
Problem 37
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All AHSME Problems and Solutions

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