[Geometry 6] Practice measuring angles

I. METHOD OF MEASURING ANGLE

To measure angle $xOy$, a protractor is placed so that its center coincides with vertex $O$ of the angle, one side of the angle (such $Ox$) passes through line 0 of the protractor. Assume that the other side of the angle (ray $Oy$) passes through line 33. Then we say measurement of angle $xOy$ is 33 degrees.

The measurement of angle $xOy$ is $33$ degrees, is denoted by $\widehat {xOy} = {33^\circ}$ or $\angle xOy = {33^\circ}$
(Tâm của thước: Center of a protractor)

II. PRACTICE MEASURING ANGLES

Find the measurement of the angles in below figures?

Both angles are $139^\circ$

You can practice more at website http://www.mathplayground.com/measuringangles.html