What are the steps to use to measure an angle using a protractor?

Answer 1

To measure an acute or obtuse angle:

1. Put the cross-hairs at the centre of the base line of the protractor on the point of the angle;
2. Align one zero on one arm of the angle (keeping the cross-hairs in place) with the circular part of the protractor over the other arm;
3. Read off the angle of the other arm with the scale that starts at 0o on the first arm.

To measure a reflex angle:

1. Measure the angle (of the small angle) between the arms as above;
2. Subtract the found angle from 360o.

Note:

The base line of the protractor is the straight line marked on the protractor that runs from 0o to 180o; half way along this line will be a perpendicular line towards the 90o mark which may touch or cross the base line - this point is the "cross-hairs".

To draw a given angle:

To draw an acute or obtuse angle:

1. Draw one arm of the angle;
2. Put the cross-hairs at the centre of the base line of the protractor on the end of the arm that forms the point of the angle;
3. Align one zero on the drawn arm of the angle (keeping the cross-hairs in place) with the circular part of the protractor where the other arm should go;
4. Mark the angle of the other arm with the scale that starts at 0o on the first arm.
5. Draw in the other arm;
6. Optional: mark the angle (between the lines) with a small arc near the point.

To draw a reflex angle:

1. Subtract the angle from 360o
2. Draw as above; except the angle is marked with a small arc round the outside of the arms (instead of between them).

Answer 2

1. Place the center of the protractor on the vertex of the angle.
2. Align the base of the protractor with one side of the angle.
3. Read the measure where the other side of the angle intersects with the protractor scale.
4. Note the measure in degrees.