What Happened Yesterday? Let’s Review!  Line  Ray  Line Segment  Angle  Vertex  Point  Triangles  Intersection

1.2 Measurement of Segments and Angles Measuring segments: Ruler or meter stick units of measure Match item being measured with proper unit U.S.: Inches, feet, yards, miles etc. Metric: km, cm, m, mm

Distance: absolute value m AB 1234 AB |2-3|or|3-2| = |-1|= |1|= 1 The length of AB = 1 cm cmcm

Measuring angles: Unit of measure: Degrees Tool: protractor

Angle measurement Angle measurement is the opening from one ray to the next ray. We usually use the inside measurement, 180 degrees or less. A full turn is a circle and measures 360 degrees.

P A R m<PAR = 90  m<A = 90  Angle measurement m<1 = 135  1 Let’s think about the measure of the angle formed by the hands of a clock at 3:00 and 4:30

Classify angles by size Acute: 0<90  Right: 90  Obtuse: 90  <180  Straight: 180 

Parts of a degree: 1 Degree = 60’ (minutes) 1 Minute = 60” (seconds) So, 87  = 87  30’ 90  = 89  59’60”

Find m<CBD A B C D m<ABD = 90  m<ABC = 74  21’10” 90  - 74  21’ 10” 15  38’50”

Congruent angles and segments Symbol: = = < have the same measure = have the same length <A = <B A 60 B 60

Congruency Tick marks show congruency A C B X ZY Can you name congruent angles and segments?

Example A B C 1 2 m<ABC = 90  m<1 = (3x+4)  m<2 = (x+6)  Find both angles! 3x x + 6 = 90 so m < 1 = 64  4x + 10 = 90 m < 2 = 26  4x = 80 X = 20

Recap! Acute Angle Congruent Angle Congruent Segments Degree Obtuse Angle Right Angle

YOUR TURN Work with a partner Pg 14 #1,2, 5-8, 10, 12, 13-16, 18