## How to measure an angle using the protractor

Note the sequence:

- The center
**O**The protractor should be placed over the vertex of the angle. - The horizontal line through the center must coincide with one of the right angles .
- We check the measure of the scale in which passes the other semi-straight .

## How to build an angle using the protractor

Observe the sequence used to construct an angle of 50º:

We draw a semi-straight .

We place the center of the protractor over the origin of the straight (A).

We identified on the protractor the point (C) corresponding to the 50º measurement.

Let us draw the straight , obtaining the angle BÂC that measures 50º.

The angles of 30º, 45º, 60º and 90º are special angles. They can be drawn with square.

Next: Reading an Angle