acute angle, angle, obtuse angle, right angle, straight angle, vertex of an angle
TEKS 7(1)(E), 7(11)(C)
An angle (∠) is a figure formed by two rays with a common endpoint. You can name the angle shown ∠ ABC, ∠ CBA, ∠ B, or ∠ 1. The vertex of an angle is the point of intersection of the two sides of an angle.
You measure angles in units called degrees (°). You can use a protractor to measure angles.
Step 1 Place the point of the protractor on the vertex of the angle.
Step 2 Make sure that the lower side of the angle passes through zero on the scale. Start measuring from zero.
Step 3 Read the scale where it intersects the higher side of the angle.
Sometimes you have to rotate the protractor to line it up with one side of an angle. The lower side of the angle should go through the zero on the protractor's scale.