Question: Can you name all the radii of the following circle ?
Answer: Radius of the circle is the distance from its center to its circumference. There could be any number of radii in a circle. A line passes through center of the circle and connects two sides of the circumference is called a diameter. A diameter is exactly twice the length of a radius.
In the diagram above, there are four radii, which are: AB, GB, CB and DB. Look closely all these radii are connected through center of the circle.
Length CD is called diameter of the circle. Straight line EF and AE are called Chord. And the Curve length of EF and AE is called as Arc (length of two points on circumference).
You need to understand these points very clearly as in the next chapters there will be many problems based on circles. Understanding circle concept in details will help to solve complex problems easily.