Some rulers are six inches (15cm) long and are called half foot ruler. We use it also to measure length of a line segment.Ī ruler is generally 1 ft (30 cm) long and is called One foot ruler. Measurement of line segmentĪ ruler is an instrument used in geometry. We can say a piece of paper from our Exercise Book is a plane. *Flat surface is called a plane in Geometry. Hence these three points A, B and C is collinear. In the figure above, points A, B and C are on the same line. Three or more points in a plane* are said to be collinear if they all lie on the same line. In the figure below, the three lines AB, CD and EF intersect each other at point O. Three or more lines passing through the same point on a plane are called concurrent lines. Point O is the point of their intersection. Let us look at the two lines AB and CD in figure above. Even if we extend these lines further, they will not touch or meet each other. In the figure above, the two lines do not intersect each other. No two points can be common to two parallel lines. If the two lines cannot meet at any point, they are called parallel lines. If the two lines on a plane meet, we say the two lines intersect and the point where they meet is called point of intersection. Two lines in the same plane either meet or do not meet. In the figure below, a line segment AB has two end points A and B. Line segment can also be a part of a line as in the figure below.Ī line-segment may be also a part of ray. Both pass through the same two points A and B. One and only one line-segment can be between two given points A and B. It starts from point A and ends at point B. In the figure above, a line segment AB has two end points A and B. A line segment is named by its two endpoints and written as line-segment AB or line-segment PQ. Let us join them by drawing a straight line. Let us mark two small dots (.) by a pencil as points A and B. It is the shortest path between the two points. A line segment is a straight line that connects two points. A section of a line is a line segment.Ī line segment has two endpoints. It starts from one point and ends at another point. A vertical line goes straight up or down.Ī diagonal line can be in any direction between horizontal line and vertical line. Both pass through the same two points A and B.Īn unlimited number of lines can be drawn passing through a given point A.Ī horizontal line goes straight left or right across. One and only one line can be drawn passing through two given points A and B. A line has no definite length.Ī line is named by any two points on it and written as line AB or line PQ. This is called line.Ī line goes without end in both directions. It indicates it can go further on both sides without end. This is a ray because a ray has one endpoint and goes without end in one direction Line The rays coming from torch or sun are examples of rays. An unlimited number of rays can be drawn in different directions from a given point In the figure above, the starts from A and the arrow denotes it can go to infinity. We say a ray has one endpoint and goes without end in one direction. It has staring point but has no end point. In Geometry also, a ray starts from a point and may go to infinity. The rays start from sun and go in all directions and reach to us. The light rays come out of it and move away. It is located at right bottom of the plan. In the figure below, there is another point A. Here it indicates this point O is located at the centre of the plane. In the figure above, O is a point as it has a definite mark. Point is denoted by a dot (.) and is named by an alphabet. Every shape is made through the combining the points.Ī small dot marked by a pencil is a point. Point is the basic building block of Geometry.
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