**Chapter Notes and Summary**

• A point does not have any length, breadth and thickness. It determines a location.• A part of a line is called a line segment. It is shortest distance between two points;

**• If two distinct lines meet at a point, they are called intersecting lines.**

**• Two parallel lines in a plane do not meet each other.**

**• A drawing (straight or non-straight) drawn without lifting pencil is called a curve.**

**• A closed curve made up of line segments only is called a polygon. In a polygon, line segments are called its**

**sides.**

**• meeting point of a pair of sides in a polygon is called a vertex of polygon.**

**• A three-sides polygon is called triangle. It is polygon with least number of sides.**

**• A four-sides polygon is called a quadrilateral.**

**• An angle is made up of two rays starting from a common end point. common point is called its vertex.**

**• A chord of a circle is a line segment joining any two points on circle.**

**• A diameter is a chord passing through centre of circle.**

**• A diameter of a circle divides its into two semi-circles.**

**• Diameter is longest chord of circle.**

**• A sector is a region in interior of a circle enclosed by an arc on one side and a pair of radii on other two**

**sides.**

**• A segment of a circle is a region in interior of circle enclosed by an are and its corresponding chord.**

**• Every angle of convex quadrilateral is less than 180º whereas in a non-convex (or concave) quadrilateral there**

**exists at least on angle whose measure is greater than 180º.**

**• Three or more lines in a plane are said to be concurrent if all of them pass through same point.**