Vocabulary Origin & Quadrants Vertex Right, Acute, & Obtuse Complementary & Supplementary Central & Inscribed Angles Arc

An ANGLE is created by rotating a ray about its endpoint (vertex). If we fit an angle to a coordinate system, the vertex is at the _______ and the initial side is the _________ This is called “Standard Position” Initial Side Terminal Side

These 2 angles are “COTERMINAL” Negative Angle (Clockwise) Positive Angle (Counterclockwise) (They end together)

Angles can be measured in DEGREES or in RADIANS (similar to feet & meters)

DEF: One RADIAN is the measure of a central angle  such that the arc length s is equal to the length of the radius r.  r s If s = r then  = 1 radian

arc length radius The radian measure of a central angle  = s r =

RadiansDegrees 1 full revolution? ½ a revolution? ¼ a revolution? s r =  60° 45° 30° ? 90° 180° 360° 2

Ex. What is the supplement of ? Ex. What is the complement of ? Ex. Find a coterminal angle for for