Difference between revisions of "2016 AIME II Problems/Problem 5"
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==Solution== | ==Solution== | ||
Note that by counting the area in 2 ways, the first altitude is <math>\dfrac{ac}{b}</math>. By similar triangles, the common ratio is <math>\dfrac{a}{c}</math> for reach height, so by the geometric series formula, we have <math>6p=\dfrac{\dfrac{ac}{b}}{1-\dfrac{a}{c}}</math>. Testing triangles of the form <math>2p+1, 2p^{2}+2p, 2p^{2}+2p+1</math>, we have <math>13, 84, 85</math> satisfy this equation, so <math>p=13+84+85=\boxed{182}</math>. | Note that by counting the area in 2 ways, the first altitude is <math>\dfrac{ac}{b}</math>. By similar triangles, the common ratio is <math>\dfrac{a}{c}</math> for reach height, so by the geometric series formula, we have <math>6p=\dfrac{\dfrac{ac}{b}}{1-\dfrac{a}{c}}</math>. Testing triangles of the form <math>2p+1, 2p^{2}+2p, 2p^{2}+2p+1</math>, we have <math>13, 84, 85</math> satisfy this equation, so <math>p=13+84+85=\boxed{182}</math>. | ||
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+ | Solution by Shaddoll |
Revision as of 19:17, 17 March 2016
Triangle has a right angle at . Its side lengths are pariwise relatively prime positive integers, and its perimeter is . Let be the foot of the altitude to , and for , let be the foot of the altitude to in . The sum . Find .
Solution
Note that by counting the area in 2 ways, the first altitude is . By similar triangles, the common ratio is for reach height, so by the geometric series formula, we have . Testing triangles of the form , we have satisfy this equation, so .
Solution by Shaddoll