Two or more straight lines which do not intersect each other at any point on the plane are called parallel lines.

Parallel lines are straight lines basically and they appear on a plane side by side. They never intersect each other anywhere on a plane because of having same angle. Therefore, if two or more straight lines have same angle, then they do not meet each other.

Similarly, the vertical distance between opposite points of them is always same due to the parallelism of the parallel lines.

$\overleftrightarrow{AB}$ and $\overleftrightarrow{CD}$ are two straight lines and they are extended infinitely but they do not intersect each other even though they are appearing side by side.

They maintain equal distance between them at all their opposite points. The reason for this is the angles of both straight lines are same.

The straight lines $\overleftrightarrow{AB}$ and $\overleftrightarrow{CD}$ are called parallel lines.

A double vertical line ($\|$) is used to represent parallelism of the lines mathematically.

The parallel symbol is displayed between straight lines to express that they both are parallel lines.

$\overleftrightarrow{AB} \,\, \| \,\, \overleftrightarrow{CD}$

It is read as $\overleftrightarrow{AB}$ parallel to the $\overleftrightarrow{CD}$.

Similarly, it can also be displayed in other way.

$\overleftrightarrow{CD} \,\, \| \,\, \overleftrightarrow{AB}$

It is read as $\overleftrightarrow{CD}$ parallel to the $\overleftrightarrow{AB}$.

List of most recently solved mathematics problems.

Jul 04, 2018

Limit (Calculus)

Evaluate $\displaystyle \large \lim_{x \,\to\, \tan^{-1}{3}} \normalsize {\dfrac{\tan^2{x}-2\tan{x}-3}{\tan^2{x}-4\tan{x}+3}}$

Jun 23, 2018

Limit (Calculus)

Evaluate $\displaystyle \large \lim_{x \to 0} \normalsize \dfrac{e^{x^2}-\cos{x}}{x^2}$

Jun 22, 2018

Integral Calculus

Evaluate $\displaystyle \int \dfrac{1+\cos{4x}}{\cot{x}-\tan{x}} dx$

Jun 21, 2018

Limit

Evaluate $\displaystyle \large \lim_{x \to \infty} \normalsize {\sqrt{x^2+x+1}-\sqrt{x^2+1}}$

Math Doubts is a best place to learn mathematics and from basics to advanced scientific level for students, teachers and researchers.
Know more

Learn how to solve easy to difficult mathematics problems of all topics in various methods with step by step process and also maths questions for practising.