entry task if ydf = 121 and dr bisects fdi find the measure of: a) ida b) yda c) rdi y d a f r i
DESCRIPTION
Parallel Lines Using the 2 parallel lines, draw a transversal that intersects both lines. Predict, based on visual inspection connections about angle pairs – Corresponding – Alternate Exterior – Alternate Interior – Same Side Interior Angles Compare your findings with your table partners Measure all 8 angles using a protractor On your paper, compare your predictions to your measurementsTRANSCRIPT
Entry Task
If ∠ YDF = 121 and DR bisects ∠FDI find the measure of:a) ∠ IDAb) ∠ YDAc) ∠ RDI
Y
D
A
F
R
I
Properties of Parallel Lines3.2
Learning Target: I can use parallel lines to prove angle relationships
Success Criteria:
I can find the measures of angles formed by parallel lines crossed by a transversal.
I can prove angles congruent using the theorems and properties of parallel lines crossed by a transversal
Parallel Lines
• Using the 2 parallel lines, draw a transversal that intersects both lines.
• Predict, based on visual inspection connections about angle pairs– Corresponding– Alternate Exterior– Alternate Interior– Same Side Interior Angles
• Compare your findings with your table partners• Measure all 8 angles using a protractor• On your paper, compare your predictions to your
measurements
Parallel Lines Cont…..
• Make a general statement about each angle pair• Share with your table partner each of the four
statements• Assign an angle pair to each student• Move to correct corner of room and share with
new group• Create a General Statement on an 8x11 piece of
paper for our Public Record
Proving Lines Parallel• Watch this Video first
• Then watch this Video
Check It Out! Example 1
Find mQRS.
mQRS = 180° – x
x = 118
mQRS + x = 180°
Corr. s Post.
= 180° – 118°
= 62°
Subtract x from both sides.
Substitute 118° for x.
Def. of Linear Pair
Find each angle measure.
Example 2: Using the Corresponding Angles Postulate
A. mECF
x = 70
B. mDCE
mECF = 70°
Corr. s Post.
5x = 4x + 22 Corr. s Post.
x = 22 Subtract 4x from both sides.
mDCE = 5x
= 5(22) Substitute 22 for x.
= 110°
Find each angle measure.
Example 3: Finding Angle Measures
A. mEDG
B. mBDG
mEDG = 75° Alt. Ext. s Thm.
mBDG = 105°
x – 30° = 75° Alt. Ext. s Thm.
x = 105 Add 30 to both sides.
Check It Out! Example 4
Find mABD.
mABD = 2(25) + 10 = 60°
2x + 10° = 3x – 15° Alt. Int. s Thm.
Subtract 2x and add 15 to both sides.x = 25
Substitute 25 for x.
Same as #1
Homework
• Homework P. 153 #7-10, 12-20,22
• Challenge - 28
