Angle & Segment Relationships

Angle & Segment Relationships

by Jennifer Fuller

Poll

Welcome to Virtual Geometry Class!

How are you feeling today?

​Today we will be reviewing basic geometry concepts

(1) Segment Length and relationships between segments

(2) Segment Addition & Subtraction Postulates

(3) ​Angle Addition & Subtraction Postulates

​(4) Measures Angles & Angle Pairs with a Protractor

​(1) Segment Length and relationships between segments

​Using the points marked on the number line above, name some segments that you see.

​

• ​*Which segment is longest?

• ​*Which segment is shortest?

• ​*Are any 2 segments the same length?

• ​*Can you make "comparison" statements about them? (>, <, =)

Multiple Choice

Which statement below is FALSE?

• NO > PQ

• OQ > NO

• OP = PQ

• NQ > PQ

​(2) Segment Addition Postulate

​The segment addition postulate states that if we are given two points on a line segment, A and C, a third point B lies on the line segment AC if and only if AB + BC = AC.

Multiple Choice

Which equation best represents the Segment Addition Postulate for 

"S is between C and D"?

Draw a picture to help.

• SC + CD = SD

• SD + SC = CD

• CD + SD = SD

​Draw it out!

​DS + SC = CD

​

​

​

​

​

​

​

​(Remember with segments DS is the same segment as SD, but NOT the same as DC)

​Let's try one together:

​Point G is on line segment FH.

Given FH=19 and FG=12,

determine the length GH

​

​1) Draw it out

​2) Label each part, include lengths

​3) Write & solve an equation for the missing piece

​

​ FG + GH = FH --> 12 + GH = 19

​

​Point T is on line segment SU. Given SU=17 and TU=14, determine the length ST.

​

​

​(3) Angle Addition Postulate

​The angle addition postulate states that if point B is in the interior of angle ADC , then. m∠ADB + m∠BDC = m∠ADC.

​

That is, the measure of the larger angle is the sum of the measures of the two smaller ones.

Fill in the Blanks

​(4) Measuring Angle Pairs

​When you read a protractor, pay close attention to . . .

​1) The center dot of the protractor aligns with the vertex of your angle

​

​2) The line on the protractor lines up with one side of your angle

​

​3) The protractor reads from 0 - 180; choose the LOGICAL answer! Is your angle acute or obtuse?

Multiple Choice

What is the measure of angle FGI?

• 180

• 162

• 28

• 18

​"Homework"

​(1) Finish Delta Math from Friday

​(2) Do today's Delta Math

​(3) Work on Project

​

​I'll see you Thursday -- we are doing "MAP" testing Thursday & Friday, and any extra time in class you can use to work on your project, so bring whatever supplies you need!

​

​These are also good days to bring a laptop ;)