- A line is a straight one dimensional geometrical figure which having no thickness and will be extended up to infinity in both the directions.
- Hence, we cannot measure the length of line.
- Line segment is the portion of line but which is having two end point on both sides.
- The length of line cannot be measured but the length of line segment is measured as it is having finite length.
- Ray is also the portion of line which is having one end point and it extends up to infinity from other end.
- The starting point of ray is called as the vertex point.
- When two rays meet at a common vertex point then angle is formed.
The types of lines are as follows:
1. Horizontal line:
- The straight line which is drawn from left to right or right to left and which is parallel to X- axis in Cartesian coordinate system is the horizontal line.
- The horizontal line is parallel to X-axis but it is having only y-intercept on the Y-axis as shown in figure.
2. Vertical line:
- The straight line which is in up and down direction and parallel to Y-axis is called as the vertical line.
- The vertical line has only x- intercept and no slope or which is undefined as shown in figure.
3. Intersecting line:
- When two or more lines crosses each other at a common point then these lines are called as intersecting lines. The common point at which they intersect is called as the intersecting point.
- Intersecting point lies on each line and it is common in all lines as shown in following figure.
4. Perpendicular line:
- When two straight lines intersect at a right angle to each other in a common point then it is called as perpendicular lines.
- The following figure shows the perpendicular lines which are having the slope m1 and m2.
- Then, m1= -1/m2
5. Parallel line:
- Parallel lines are the straight lines which do not intersect each other at any point and will be extended up to infinity in a plane.
- The following figure shows the parallel lines with slope m1 and m2.
- Then, for parallel lines,
- m1 = m2
6. Curved line:
- The lines which are not straight but somewhat bent are the curved line.
- The following figure shows the curved line.
7. Skew line:
- Skew lines are the lines which are not parallel and also not intersecting.
- Hence, they can exist only three or more dimensions.
- The following figure shows the skew line.
8. Dotted line:
- Dotted line is made up of a series of dots along a straight direction.
- The following figure shows the dotted line.
9. Diagonal line:
- Diagonal line is the line which is somewhat slant and join the two opposite corners of the shape.
- In following figure the line AB is the diagonal line.
Fig: Types of lines