Problem 10 · 2015 Math Kangaroo
Easy
Geometry & Measurement
perimeter
The side lengths of a triangle are 6, 10 and 11. An equilateral triangle has the same perimeter as this triangle. How long is one side of the equilateral triangle?
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Answer: D — 9
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Hint 1 of 2
First find the perimeter of the given triangle.
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Hint 2 of 2
An equilateral triangle with the same perimeter has each side equal to that perimeter divided by 3.
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Approach: match perimeters then divide by 3
- The triangle's perimeter is 6 + 10 + 11 = 27.
- An equilateral triangle with the same perimeter also has perimeter 27.
- Each of its three equal sides is 27 / 3 = 9.
- So one side is 9 (D).
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