Geometry

- A
**point**determines a location. The tip of a compass, the sharpened end of a pencil, the pointed end of a needle, etc., are the examples of points. Generally, points are denoted by capital letters. - A
**line segment**corresponds to the shortest distance between two points. The line segment joining the points P and Q is denoted as .

- A
**ray**is a portion of a line, which starts at one point and goes endlessly in a direction.

This ray is denoted as . Arrow head is towards Q since it is extended along Q.

- When a line segment PQ is extended indefinitely on both sides of points P and Q, it becomes a
**line**, . Line is usually denoted by small letters*l, m, n.*

- Two lines
*l*and*m*are said to be**intersecting lines**, if they intersect at a point.

- Two lines are said to be
**parallel lines**, if they never intersect each other. We can represent the given lines as*l*||*m.*

- A
**plane**is a flat surface having length and width, but no thickness. We can say that a plane is a flat surface, which extends indefinitely in all directions. For example, surface of a wall, floor of a ground, etc. **Incidence properties in a plane:**- An unlimited number of lines can be drawn passing through a given point.
- There is exactly one line passing through two distinct points in a plane.
- Points lying on the same line are known as collinear points and the points which do not lie on the same line are called non-collinear points.
- Three or more lines passing through a common point are known as concurrent lines and that point is known as point of concurrence.

- One complete turn of the hand of a clock is one revolution. The angle of one revolution is called a
**complete angle.**

- A right angle is of a revolution and a straight angle is of a revolution.

- 1 complete angle = 2 straight angles = 4 right angles
- 1 straight angle = 2 right angles
- If an angle measures less than a right angle then it is know…

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