A circle is a two-dimensional figure/shape whose all points in a plane are equidistant from the center. It is often bounded by a curved line, with many real-life objects, including tires, coins, and some dishes, assuming the shape.

Over time, circles have inspired various innovations and mathematical calculations that have helped shape the current world. Here are some amazing circle (shape) facts you probably didn’t know.

1. There Are Different Parts of a Circle

Depending on their positions and properties, circles have different parts. The most common ones include annulus (the region bounded by two concentric circles), sectors, segments, diameters, radii, and arcs. Others are tangents, chords, and secants.

2. The Radius of a Circle Is Very Significant

The radius of a circle is half its diameter. It determines the circumference and area of the shape and is critical for mathematical calculations. For instance, to calculate the circumference of a circle, you will need to multiply the radius and pie (π) by 2. On the other hand, the formula for calculating the area of a circle is  (where r represents the radius).

3. The Symbol for “Correct” in Japan Is a Circle

Unlike most parts of the world, japan uses a circle to indicate something, say an equation or answer, is correct. On the contrary, the checkmark symbol means the opposite (incorrect). This explains why some gaming consoles used/use “O” for confirming and “X” for canceling.

4. A Circle Has Several Properties

All circles have the same basic properties. For example, the outer line of a circle is equidistant from the center. Also, the diameter is double the radius and the largest circle chord.

5. There Is a Reason Why Cats and Dogs Circle around Before Sleeping

Scientists have it that the reason why cats and dogs circle before bedding might be tied to their wild ancestors. To survive, the animals positioned themselves in the wind direction to pick up predator scents. Additionally, the circular position allowed the animals to better monitor the environment.

6. You Can Draw A Circle Using a Compass

While it’s true that you can draw a circle using your free hand, a geometric compass can help generate the perfect circular shape. After determining the size of the circle that you want to draw, adjust the compass to match its radius.

Identify a middle point (O) on your drawing material and place the sharp end of the compass on it. Rotate the compass to mark the area using the pen or pencil attached to the tool until a perfect circle is drawn. Other methods of drawing a circle include using circular objects such as bottle tops and a thread and a nail.

7. There Are Competitions for Freehand Circle Drawing

Over time, people have engaged in freehand circle drawing competitions. Here, participants compete to see who draws the best circles without using tools other than a pen, pencil, or marker.

Most of these events are primarily for charity, though. For instance, Alexander Overwijk, a Canadian teacher who went viral for claiming he could hand-draw a circle, hosted a World Freehand Circle Drawing Competition to fundraise for the Canadian Cancer Society.

8. There Is a Divination Where Congregants Spin in Circles

Gyromancy is a form of divination where a congregant walks in a circle drawn on the ground until they fall over because of dizziness. Often marked by alphabets, the point of the circle where the individual falls is used to interpret the results of upcoming events.

9. There Are Ant Circles

Formally known as ant mills, ant circles are a phenomenon where a group of army ants form a continuously rotating circle until they die of exhaustion. Usually, the ants in these circles are separated from the main group during a foraging spree. After losing their way, they follow each other in circles, otherwise known as death spirals.

10. Circles Have No Corners or Edges

Being a round-shaped figure, circles have no corners or edges. It is often described as a closed, curved, and two-dimensional shape. Also, circles have infinite sides.

11. A Full Circle is 360 Degrees

A full circle takes up 360 degrees, while a half circle measures 180 degrees. If anything, most angular measurements in radians or degrees are always given with a circle in mind.

12. There Is a Strange Circle Known As the Tulsa Center of the Universe

Located on a pedestrianized bridge in Tulsa, Oklahoma, the Tulsa Center of the Universe is a circle capable of amplifying sound. People visit the region, stand in the middle of the circle, make a noise, and wait to hear it echoing back several times louder. Interestingly, those outside the circle can’t hear a thing.

13. A Fairy Circle Consists of Mushrooms Growing in a Circle

Also known as a fairy ring, a fairy circle is a group of mushrooms growing in a circular shape. Mainly found in forested areas, these mushrooms target the nutrients inside the area they cover. They have been subject to different myths and folklore over time.

14. The Circular Disk in Bangladesh’s Flag Is Often Slightly toward the Hoist

Watching Bangladesh’s flag fly gives the illusion that the circular disc is at its center. However, this is not true; the disc is often slightly toward the hoist, giving it a central appearance when the flag is flying.


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Last Update: October 19, 2023