Name: Construction of Angles Using Protractor
Uploaded: 2019-07-19
Duration: 4 min 7 s
Description: We know that an angle is formed when two rays join at a common point. In this video session, learn how to construct angles using a basic geometry tool called a protractor.

Question

Draw any two intersecting lines. Construct angle bisectors of one pair of vertically opposite angles. Measure the angle formed by the two bisectors.

Accepted Answer

Draw two lines $AB and CD$ intersecting each other at point $O .$ The pairs of vertically opposite angles are;

$∠ AOD, ∠ COB, ∠ AOC & ∠ BOD$ .

We will take a pair $∠ AOD and ∠ COB$ . First, Draw an angle bisector of $∠ AOD$ and then $∠ COB$ .

Step $1$ : Take a length smaller than $OA$ in compass. Take $O$ as centre and draw an arc cutting both the lines $OA and OD$ .

Step $2$ : Take the point as centre where it has cut the line $AB$ , and with the same radius draw an arc. With same radius and the centre as a point where first arc has cut line $CD$ ,draw an arc intersecting this arc at point $E$ .

Step $3$ : Repeat the same steps for $∠ COB$ and draw an arc cutting each other at $F .$

Step $4$ : Draw a line joining points $E and F$ . This line is an angle bisector of opposite angles $AOD and COB$ .

Step $5$ : When we measure the angle formed by two bisectors, it is a straight line hence the angle $EOF$ is $180 ˚$

Hence, the angle formed by the two bisectors is $180 ° .$

Draw any two intersecting lines. Construct angle bisectors of one pair of vertically opposite angles. Measure the angle formed by the two bisectors.

Important Questions on Practical Geometry

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