Difference between revisions of "2018 AMC 10A Problems/Problem 16"
Elements2015 (talk | contribs) (→Solution) |
Elements2015 (talk | contribs) (→Solution) |
||
Line 10: | Line 10: | ||
==Solution== | ==Solution== | ||
− | + | <asy> | |
pair A, B, C, E, P; | pair A, B, C, E, P; | ||
A=(-20, 0); | A=(-20, 0); | ||
Line 19: | Line 19: | ||
draw(A--B--C--cycle); | draw(A--B--C--cycle); | ||
draw(B--P); | draw(B--P); | ||
− | dot(" | + | dot("$A$", A, SW); |
− | dot(" | + | dot("$B$", B, SE); |
− | dot(" | + | dot("$C$", C, NE); |
− | dot(" | + | dot("$P$", P, S); |
− | + | </asy> | |
As the problem has no diagram, we draw a diagram. The hypotenuse has length <math>29</math>. Let <math>P</math> be the foot of the altitude from <math>B</math> to <math>AC</math>. Note that <math>BP</math> is the shortest possible length of any segment. Writing the area of the triangle in two ways, we can solve for <math>BP=\dfrac{20\cdot 21}{29}</math>, which is between <math>14</math> and <math>15</math>. | As the problem has no diagram, we draw a diagram. The hypotenuse has length <math>29</math>. Let <math>P</math> be the foot of the altitude from <math>B</math> to <math>AC</math>. Note that <math>BP</math> is the shortest possible length of any segment. Writing the area of the triangle in two ways, we can solve for <math>BP=\dfrac{20\cdot 21}{29}</math>, which is between <math>14</math> and <math>15</math>. | ||
Revision as of 18:49, 3 March 2018
Right triangle has leg lengths and . Including and , how many line segments with integer length can be drawn from vertex to a point on hypotenuse ?
Solution
As the problem has no diagram, we draw a diagram. The hypotenuse has length . Let be the foot of the altitude from to . Note that is the shortest possible length of any segment. Writing the area of the triangle in two ways, we can solve for , which is between and .
Let the line segment be , with on . As you move along the hypotenuse from to , the length of strictly decreases, hitting all the integer values from (IVT). Similarly, moving from to hits all the integer values from . This is a total of line segments. (asymptote diagram added by elements2015)
See Also
2018 AMC 10A (Problems • Answer Key • Resources) | ||
Preceded by Problem 15 |
Followed by Problem 17 | |
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 |
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions.