Post on 02-Jan-2016
Holt Geometry
3-2 Angles Formed by Parallel Lines and Transversals
1
2
What if the lines are parallel?
Holt Geometry
3-2 Angles Formed by Parallel Lines and Transversals
Postulate or Theorem Name What it says Key Words Picture
If 2 parallel lines are cut by a transversal, then…
Corresponding Angles Postulate
…the corresponding angles are congruent.
Parallel linesTransversalCorresponding angles
HANDBOOK PAGE 15
Holt Geometry
3-2 Angles Formed by Parallel Lines and Transversals
m
n
1
2
34
5
7
6
8
If m<8 = 61˚, find the measures of all other numbered angles.
Example 1)
Holt Geometry
3-2 Angles Formed by Parallel Lines and Transversals
m
n
1
2
34
5
7
6
8
Alternate Interior angles are ____________.
Alternate exterior angles are ____________.
Same-side interior angles are ____________.
Example 2)
Holt Geometry
3-2 Angles Formed by Parallel Lines and Transversals
Alternate Interior Angles Theorem
…the alternate interior angles are congruent.
Parallel linesTransversalAlternate interior angles
Alternate Exterior Angles Theorem
…the alternate exterior angles are congruent.
Parallel linesTransversalAlternate exterior angles
Same-side Interior Angles Theorem
…the same-side interior angles are supplementary.
Parallel linesTransversalSame-side interior anglesSupplementary
Holt Geometry
3-2 Angles Formed by Parallel Lines and Transversals
Find each angle measure.
A. mDCE
B. mCBG
Holt Geometry
3-2 Angles Formed by Parallel Lines and Transversals
Given m3 = 3x-1 and m5 = x+5.
Find m1.
Example 3)
Holt Geometry
3-2 Angles Formed by Parallel Lines and Transversals
Given m3 = 2(x-35) and m4 = x+15.
Find m5.
Example 4)