How to Find an Angle in 2D Space

Measure angles using a protractor.

Learn to determine angles in two-dimensional space to excel in math class. Also, angle measure is an important skill for woodworking and home construction projects. Angles are typically measured in degrees where 360 degrees equals a full turn, or circle. The standard device used for determining angles on a two-dimensional plane is a protractor. A half-circle in shape, a protractor has angle increments marked on its curved edge from zero to 180 degrees from left to right and also from right to left.

Things You'll Need

• Protractor

Instructions

1. Align the flat edge of the protractor along one straight line of the angle to be measured.

2. Slide the protractor until the vertex, or intersection point, of the two lines making the angle appears under the circle on the device. Frequently the circle is also accompanied by cross hairs.

3. Note the degree mark crossed by the line making up the angle. If the angle opens to the left of the protractor, use the left-to-right degree scale for the reading. If the angle opens to the right of the protractor, use the right-to-left degree scale for the reading.

Tips & Warnings

• A straight line measures 180 degrees.

References

• Maths Teacher: Angles