**Geometry Chapter 1.4 Angles and their Measures:**

**I) Vocabulary and Postulates:**

**A) Angle**- consists of two different rays that have the same initial point.

**1) Vertex**- the initial point of the angle.

**2) Rays of an angle**- the sides of the angle.

**B) Congruent Angles**- angles that have the same measure.

**C) Angle Addition Postulate**- If P is on the interior of angle RST, then measure of angle RSP + measure of angle PSP = measure of angle RST.

**D) Acute Angle**- an angle that's measure is between zero and ninety degrees.

**E) Right Angle**- an angle that's measure is 90 degrees.

**F) Obtuse Angle**- an angle that's measure is between 90 degrees and 180 degrees.

**G) Straight Angle**- an angle that's measure is 180 degrees.

**H) Adjacent Angles**- two angles are adjacent angles if they share a common vertex

**AND**a common side, but do not have any common interior points.