Geometry Section 1.4 Angles and Their Measures

An *angle is the figure formed by the union of two rays with a common endpoint. The rays are called the ____ of the angle and their common endpoint is the _____ of the angle. sides vertex

The same angle can be named in different ways: 1) 2) 3) by 3 points, with the middle point being the vertex by just the vertex – must have only one angle with this vertex

The same angle can be named in different ways: 1) 2) 3) by 3 points, with the middle point being the vertex by just the vertex – must have only one angle with this vertex by using a number placed in the interior near the vertex

Angles are measured using a __________. A common unit used for measuring angles is the ______. Radians and gradients are also used. protractor degree

We write ______to represent the measure of. Postulate 1.3.2: Two angles are congruent iff Tick marks are used to indicate congruent angles in a figure. their measures are equal.

We write ______to represent the measure of. Postulate 1.3.2: Two angles are congruent iff Tick marks are used to indicate congruent angles in a figure. their measures are equal.

Angles are classified according to their measure. An *acute angle is an angle whose measure is A *right angle is an angle whose measure is between 0 and 90 degrees. exactly 90 degrees.

To indicate a right angle in a figure, place a small square at the vertex. Perpendicular lines are two lines that intersect To indicate that is perpendicular to, we write _________ to form right angles.

An *obtuse angle is an angle whose measure is A *straight angle is an angle whose measure is between 90 and 180 degrees. exactly 180 degrees.

The Angle Addition Postulate is similar to the Segment Addition Postulate. Postulate 1.3.3: Angle Addition Postulate: If S is in the interior of, then

An *angle bisector is the ray which divides an angle into two congruent angles.

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