# Chapter 10 Circles Notes for Class 9th Maths

0
720

Chapter 10 Circles

• Circles and its Related Terms : A Review
• Angle Subtended by a Chord at a Point
• Perpendicular from the Centre to a Chord
• Circle through Three Points
• Equal Chords and their Distances from the Centre
• Angle Subtended by an Arc of a Circle
• Circle- circle is locus of such points which are at equidistant from a fixed point in a plane.
• Concentric circle- Circle having same centre called concentric circle.
• Two arc of a circle called congruent if they have the same degree measure.
• If two arc equal then their corresponding chords are equal.
• The perpendicular from centre to chord of circle, it bisects the chord and converse.
• There is one and only one circle passing through three non-collinear points.
• Equal chords of circle are equidistant from centre.
• The angle subtend by an arc at the centre of circle is twice the angle which subtend at remaining part of circumference.
• Any two angles in the same segment of the circle are equal.
• Angle of semicircle is right angle.
• Equal chords of circle subtend equals angle at the centre of circle.
• If the all vertices of a quadrilateral lie on the circumference of circle, then quadrilateral called cyclic.
• In a cycle quadrilateral the sum of opposite angles is 180o and converse.
• The exterior angle of a cycle quadrilateral is equal to the opposite interior angle.