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counting and probability intermediate
Problem
How many (non-congruent) isosceles triangles exist which have a perimeter of 10 and integer side lengths?
Solution
Let be the measure of the each of the equal sides. Since the perimeter is 10 units, the side lengths measure , , and units. Since the third side length must be positive, we have which implies . By the triangle inequality, the sum of the two equal sides must exceed the third side. Solving gives . There are integers strictly between 2.5 and 5.
Final answer
2