Circles - Revision Notes

 CBSE Class 10 Mathematics

Revision Notes
CHAPTER 10
CIRCLES

  1. Tangent to a Circle
  2. Number of Tangents from a Point on a Circle
  3. Miscellaneous Questions
  • 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.