Name: Measure of an Angle
Uploaded: 2019-07-19
Duration: 1 min 48 s
Description: An angle made by two line segments is measured using a geometrical tool called the protractor. A complete angle around a point is 360 degrees. Watch this vid...

Question

Use a protractor to draw an acute angle, a right angle and an obtuse angle.

Accepted Answer

To draw an acute angle:

An angle whose measure is less than $90 °$ is called an acute angle.

Step $1$ : Draw a straight line segment $BC$ .

Step $2$ : Place the centre point of the protractor on the vertex $B$ .

Step $3$ : Adjust the baseline of the protractor so that it is aligned with the line $BC$

Step $4$ : Take any reading below $90 °$ from the inner semi-circle, for example, $72 °$ .

Step $5$ : Mark the point as $A$ and join $BA$ .

Thus, $∠ ABC$ is an acute angle of $72 °$ .

To draw a right angle:

An angle whose measure is $90 °$ is called a right angle.

Step $1$ : Draw a ray $OA$ .

Step $2$ : Place the centre of baseline of the protractor on point $O$ and align line $OA$ with the baseline of the protractor.

Step $3$ : Mark $B$ at the reading of $90 °$ .

Step $4$ : Join $OB$ .

Thus, $∠ AOB$ is a right angle.

To draw an obtuse angle:

An angle whose measure is more than $90 °$ but less than $180 °$ is an obtuse angle.

Step $1$ : Draw a straight horizontal line (a reference line), that will contain one of the rays of the angle.

Step $2$ : Place the centre point of the baseline of the protractor on the left edge of the line.

Step $3$ : Adjust the baseline of the protractor so that it is aligned with the reference line.

Step $4$ : Take any reading between $90 °$ and the baseline of the protractor, for example, $115 °$ .

Step $5$ : Mark the point with a dot outside the protractor at $115 °$ and join the point to the left edge of the reference line. An obtuse angle is formed.

Thus, $∠ ABC$ is an obtuse angle of $115 °$ .

Use a protractor to draw an acute angle, a right angle and an obtuse angle.

Important Questions on Angles

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