class 10 maths chapter 10 circles

• Circle: A circle is a collection of points in a plane which are at a constant distance from a fixed point.
• Centre: The fixed point is called a centre.
• Radius: The constant distance is called the radius.
• Diameter: Twice of radius is called the diameter.
• Chord: The line joining two points on the circumference of the circle is called a chord. The longest chord is the diameter of the circle.
• Sector of a circle: The region enclosed by two radii and the corresponding arc is called a sector of the circle.
• Segment of the circle: The region bounded by an arc and the corresponding chord is called the segment of the circle.

1. Tangent to a Circle: It is a line that intersects the circle at only one point.
2. Point of contact: The common point between the circle and the tangent is called the point of contact.
3. Secant: A line which has only two points common to a circle is called the secant.
4. There is only one tangent at a point of the circle.
5. No tangent can be drawn from a point inside the circle.
6. The tangent at any point of a circle is perpendicular to the radius through the point of contact.
7. The lengths of tangents drawn from an external point to a circle are equal.