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1995 AIME Problems/Problem 9

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Problem

Triangle is isosceles, with and altitude Suppose that there is a point on with and Then the perimeter of may be written in the form where and are integers. Find

Solution

Let , so . Then, \frac{\tan 3x}{\tan x}=\frac{CM/1}{CM/11}=11. Expanding using the angle sum identity gives \tan 3x=\tan(2x+x)=\frac{3\tan x-\tan^3x}{1-3\tan^2x}. Thus, \frac{3-\tan^2x}{1-3\tan^2x}=11. Solving, we get . Hence, and by the Pythagorean Theorem. The total perimeter is . The answer is thus .

See also

1995 AIME (ProblemsResources)
Preceded by
Problem 8
Followed by
Problem 10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
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