This is an introductory lesson about circles.
• to define and explain the concept of a circle;
to identify the different parts of a circle;
to explain the relation between the radius and diameter of a circle;
to teach students how to solve simple problems involving radius and diameter.
The idea of a circle, the basis for the wheel, has been known since the beginning of recorded history. Early scientists thought that there was something perfect or divine about circles.
In modern times, we generally refer to a circle as a simple shape of geometry. It consists of points in a plane that are all the same distance from a given point. The given point of a circle is called the center. The perimeter of a circle is known as the circumference of a circle. We can see how these three terms apply to a circle by looking at the picture below.
The distance from the center of a circle to any point along the circumference of a circle is called the radius. The diameter of a circle is a line whose endpoints touch the circumference of a circle. This line must also pass through the center of the circle.