Question 1044727
Circumference is the length of the boundary of a circle. It's the same as perimeter for the square.
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Imagine a square with a circle inside, like the drawing below. The perimeter of the square is side*4. The circle has a diameter that's the same length as the side of the square that contains it. But the circle is smaller around the corners. 
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How much smaller? Well, someone figured it out a very, very long time ago:
The perimeter of the square is side*4
The perimeter (circumference) of the circle is diameter*3.1416... This number, 3.1416..., is the irrational number Pi. If you want to know why it's called irrational send me a note.
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If your circle has a radius of 12, the circumference is 2*12*Pi = 75.4 Check your numbers, because this in not one of the choices you have.
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*[illustration inscribed_circle.JPG]