10. Circles

A circle is a set of all points in a plane that are at an equal distance from a fixed point called the centre. In this chapter, students study the important properties of tangents to a circle. A tangent is a straight line that touches the circle at exactly one point, known as the point of contact.

 

The chapter explains key theorems such as the tangent at any point of a circle is perpendicular to the radius at that point, and that the lengths of tangents drawn from an external point to a circle are equal. These properties help students solve various geometric problems and understand how circles are used in design, engineering, and practical constructions.