### Theory:

Intersecting lines:

When two lines cross each other and share a common point is known as the Intersecting line.

The above figure shows intersecting lines $$AB$$ and $$CD$$. Where two-line $$AB$$ and $$CD$$ intersect at a common point ‘$$O$$’.
Example:
We can see that the pair of metal blades in the scissor intersecting at a common point. There are many other day-to-day examples of this concept.

Parallel lines:

When two lines are in the same plane and will never intersect each other is known as Parallel lines.

The above figure shows parallel lines $$AB$$ and $$CD$$. Where two lines $$AB$$ and $$CD$$ are in the same plane but will never intersect each other and hence are termed as parallel lines.
Example:
We can see that the garage shelf parallel to each other. There are many other day-to-day examples for this idea.

Concurrent lines:

When set of lines are said to be concurrent lines if they all intersect at the same point.

The above figure shows the concurrent lines $$AB$$, $$CD$$, $$PQ$$ and $$RS$$ because they all intersect at a single point $$O$$. Thus, the concurrency of point is $$O$$.
Example:
We can see that the orange pulps insect each other at a point $$P$$. There are many other day to day examples of this idea.

Perpendicular lines:

When they meet (or intersect), two lines are said to be perpendicular to each other, and the angle between them is a right angle, that is, $$90°$$.

The above figure shows the perpendicular lines $$AB$$ and $$CD$$, and it is written as $$AB Ʇ CD$$.
Example:
We can see that windowpane intersect a line at $$90°$$. There are many other day-to-day examples for this idea.