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Three Sides
A triangle has 3 sides. To find its perimeter, add all three sides. A triangle with sides 3, 4, and 5 has perimeter 3+4+5=12. If all three sides are equal (called equilateral), you can multiply: 3 x side.
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Mathematics — Perimeter: Measuring Around Shapes
A triangle has 3 sides. To find its perimeter, add all three sides. A triangle with sides 3, 4, and 5 has perimeter 3+4+5=12. If all three sides are equal (called equilateral), you can multiply: 3 x side.