Perimeter facts for kids
In geometry, perimeter is the total distance around the outside of a flat object. Think of it like walking along the edge of a shape and measuring how far you walked.
For example, a square has four sides that are all the same length. If a square has sides that are each 2 inches long, its perimeter would be 8 inches. You get this by adding up all the sides: 2 + 2 + 2 + 2 = 8 inches.
Real-life objects also have perimeters. Imagine a football field. It's 360 feet long and 160 feet wide. To find the perimeter of the field, you would add up all its sides: 360 + 160 + 360 + 160 = 1040 feet. That's the total distance around the field!
What is Circumference?
The perimeter of a circle has a special name: circumference. You can figure out a circle's circumference using its diameter and a special number called Pi.
Understanding Pi
Pi (written as π) is a very important number in math. It's about 3.14159, but it actually goes on forever with no repeating pattern! For most calculations, using 3.14 or 3.14159 is accurate enough.
To find the circumference of a circle, you multiply its diameter (the distance straight across the circle through its center) by Pi. So, if a circle has a diameter of 10 inches, its circumference would be about 10 multiplied by 3.14, which is 31.4 inches.
Images for kids
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If the diameter of a circle is 1, its circumference equals π.
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The more one cuts this shape, the lesser the area and the greater the perimeter. The convex hull remains the same.
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The Neuf-Brisach fortification perimeter is complicated. The shortest path around it is along its convex hull.
See also
In Spanish: Perímetro para niños
