Answer:
5π, about 15.708 units
Explanation:
A 3-4-5 triangle is a right triangle. When a circle circumscribes a right triangle, the hypotenuse is the diameter of the circle. The circumference of a circle is given by ...
C = πd
For a diameter of 5 units, the circumference is ...
C = π(5) = 5π = 15.708 . . . units
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Additional comment
The (3, 4, 5) triple is one of the first Pythagorean triples you run across. It is the smallest integer triple, and the only primitive triple with values in an arithmetic sequence. You can show this is a Pythagorean triple by ...
3² + 4² = 9 +16 = 25 = 5²
That is, these numbers satisfy the Pythagorean theorem relation for sides of a right triangle.