A circle is a round shape that is a closed curve. All points on the curve are the same distance from a central point. The center is the fixed point in the middle, and the radius is the distance from the center to any point on the circle.
A circle has several important parts. The center is the fixed point in the middle. The radius is the distance from the center to any point on the edge. The diameter is the distance straight across the circle through the center. The circumference is the perimeter or the distance around the circle.
Circles have two important formulas. The circumference, which is the distance around the circle, equals two pi times the radius. The area, which is the space inside the circle, equals pi times the radius squared. Pi is approximately three point one four one five nine.
Circles are everywhere in our daily lives. We see them in wheels on cars and bicycles, in clocks and watches that tell time, in coins and buttons we use every day. Pizza slices come from circular pizzas, and we eat from circular plates. Even the sun and moon appear as circles in the sky, and many sports use circular balls and rings.
To summarize what we have learned about circles: A circle is a round closed curve where all points are the same distance from the center. The key parts include the center, radius, diameter, and circumference. We use important formulas like circumference equals two pi r and area equals pi r squared. Circles are found everywhere in our daily lives and in nature around us.