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Objective: Students will be able to use angle postulates and classify angles. 1.4 Angles and Their Measures. Vocabulary. Angle – formed by two rays connected with the same initial point. Vertex – the “initial point” of an angle Congruent Angles – two angles with the same degree measure
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Objective: Students will be able to use angle postulates and classify angles. 1.4 Angles and Their Measures
Vocabulary • Angle – formed by two rays connected with the same initial point. • Vertex – the “initial point” of an angle • Congruent Angles – two angles with the same degree measure • Interior – inside (of an angle) • Exterior – outside • Acute Angle – angle between 0 and 90 • Obtuse Angle – angle between 90 and 180 • Right Angle – angle which = 90 • Straight Angle – angle which = 180 • Adjacent Angles – Angles which share a side and vertex
Naming the angle • Three ways to name the angle: <B, < ABC, or <CBA. Vertex has to be in the middle. • Classify as acute/obtuse/right/straight • ACUTE • Name the vertex and sides • Vertex = B, Sides = BA, CB
Postulates • Angle Addition Postulate – If D is inside < ABC, then <ABD + <DBC = <ABC • Protractor Postulate – when using a protractor, the measure of <WOY = to the positive difference of OW and OY
Examples • Ex 1) If <ABD = 25 and <DBC = 57, what is <ABC? • 82 • Ex 2) If < ABC = 88 and <DBC = 33, what is <ABD? • 55
Assignment • p. 29 1-22all, 26-28all, 35-37all, 54