Linear pair of angles — lesson. Mathematics CBSE, Class 7.

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Let us discuss what linear pair of angles are.

Definition:

Linear pair is a type of angle formed by two adjacent angles, whose non-common sides are opposite rays.

In other words, the sum of the linear pair of angles is supplementary (

$180^{\circ}$ ).

In the figure, the sum of the linear angles

$POR$ and

$ROQ$ is equal to

$180^{\circ}$ .

That is,

$a + b = 180^{\circ}$ .

Example:

$x$ and

$y$ are the measures of linear pair of angles, then find the value of

$y$ given

$x$

$=$

$65^{\circ}$ .

Solution:

Given that,

$x$

$=$

$65^{\circ}$ .

By the property of linear pair of angles,

$x$

$+$

$y$

$=$

$180^{\circ}$ .

$\Rightarrow 65^{\circ} + y = 180^{\circ}$

$\Rightarrow y = 180^{\circ} - 65^{\circ}$

$\Rightarrow y = 115^{\circ}$

Some real life examples:

The following are some real-life examples where we can observe linear pair of angles.

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5. Linear pair of angles