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5.1 Angles and Radian Measure. ANGLES. Ray – only one endpoint Angle – formed by two rays with a common endpoint Vertex – the common endpoint of an angle’s initial and terminal sides. -Vertex @ origin -Initial side lies along positive x-axis. QUADRANTS.
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ANGLES • Ray – only one endpoint • Angle – formed by two rays with a common endpoint • Vertex – the common endpoint of an angle’s initial and terminal sides. -Vertex @ origin -Initial side lies along positive x-axis
QUADRANTS When in standard position, an angle’s terminal side lies in a quadrant.
Quadrantal Angle Not in a quadrant. Terminal side is on either the x- or y-axis.
MEASURING ANGLES USING DEGREES • Acute • Right • Obtuse • Straight
MEASURING ANGLES IN RADIANS • One radian is the measure of the central angle of a circle that intercepts an arc equal in length to the radius of the circle.
Ex #1: RADIAN MEASURE • ϴ = • A central angel, ϴ, ina circle of radius 12 feet intercepts an arc of length 42 feet. What is the radian measure of ϴ?
MEASURING ANGLES IN RADIANS • One radian is the measure of the central angle of a circle that intercepts an arc equal in length to the radius of the circle.
Radians and Degrees Ifϴ = what is the angle of the entire circle? REMEMBER: Circumference = 2πr
CONVERSION • Degrees Radians Degrees * • Radians Degrees Radians *
Ex #2-3 • CONVERT TO RADIANS: • CONVERT TO DEGREES: • radians • radians • radian
Drawing Angles in Standard Position • Ex #4: Draw the following angles
Drawing Angles in Standard Position • Ex #4: Draw the following angles
FINDING COTERMINAL ANGLES NOTICE: YOUR BOOK ASKS FOR POSITIVE ANGLES LESS THAN 360
HOMEWORK • Pg. 480 #1-55 odd + pg. 476 Checkpoint #5 (you’ll need to read Example 5 in order to do the checkpoint)