Drawing angles by using a protractor

Drawing angles by using a protractor

An angle can be drawn by using a protractor. The procedure for drawing angles is not different from the procedure for measuring angles.

Example

Draw an angle that measures 30°.

Solution

1. Draw a line segment OP. Draw a line segment and label it OP.

2. Mark the vertex point O. Put a point on the line segment where you would like the angle to appear and call it O.

3. Align the protractor. Place the protractor so that its center aligns with point O and its baseline lies along the ray OP.

4. Mark 30°. Locate 30° on the inner scale and place a point at this mark.

5. Draw the angle. Join point O to the point at 30°.

6. Verify the result. The angle ∠POR obtained is 30° as shown in the following figure.

Angle of 30 degrees

Example 2

Draw ∠AOB = 45°; OA = 8 cm and OB = 7 cm.

Solution

1. Draw a straight line. Draw a straight line on your paper.

2. Mark point O and measure OA. Put point O on the line where you would like the angle to appear. Measure 8 cm from O along the line to get point A, so OA = 8 cm.

3. Align the protractor. Place the protractor on the figure so that the baseline from 0° to 180° lies along OA. The center of the protractor must be at point O.

4. Mark 45°. Locate 45° on the scale and indicate it with a point.

5. Measure OB. Measure a line segment of length 7 cm from O to the point at 45° to get point B, so OB = 7 cm.

6. Complete the angle. Join point O to point B. The resulting angle is as shown in the following figure.

Angle of 45° with OA = 8 cm and OB = 7 cm