Circles Class 9

Circles class 9 – The collection of all points equidistant from a fixed point in a plane is called circle. A plane is divided by the circle into 3 parts, namely, the interior and exterior of circle and the circle itself. A chord is a line passing from one point to another on the circumference of a circle. Diameter is chord that passes through the center. The perimeter of a circle is known as circumference. Chords equal in length subtend equal angles at centre. Similarly, the chords are equal if the angles subtended by chords are equal at the centre. The perpendicular drawn on a chord from centre bisects the chord. Similarly, the line is perpendicular if it is drawn from centre to bisects the chord. Only one circle can pass through 3 non-collinear points. Chords equal in length are equidistant from the centre. Similarly, Chords are equal if they are equidistant from centre. In a cyclic quadrilateral, the sum of pair of angles opposite to each other is 180 degree. Angles subtended by same line segment are equal. If chords of a circle are equal in length, then the corresponding arcs will be congruent. Similarly, if arcs are congruent, then the corresponding chords will be equal.

Circles class 9 Examples

Circles Class 9

Circles Class 9

Circles Class 9

Circles Class 9

Circles Class 9


Practise This Question

Find the surface area of the following figure if it is folded along the dotted lines. (all the measurements are in cm)