Post on 19-Jan-2016
transcript
Properties of Parallel Lines
Objectives: To identify angles formed by two lines and a
transversal To prove and use properties of parallel lines
Agenda-E BlockOHomework Check [10 min]OWarm Up [10 min]OProperties of Parallel Lines [30 min]OPair Practice [35 min]
Agenda - F BlockOHomework Check [10 min]OConstruction Practice [20 min]
OCollected and Graded for accuracy.
OProperties of Parallel Lines [20 min]
OPair Practice [35 min]
Warm Up – Try this PSAT question!
Warm Up –Try this PSAT question!
Identifying Angles O A transversal is a line that intersects two
coplanar lines at two distinct points. O Pairs of the eight angles have special names
as suggested by their positions.
Corresponding Angles Postulate
O If a transversal intersects two parallel lines, then corresponding angles are congruent.
Alternate Interior Angles Theorem
O If a transversal intersects two parallel lines, then alternate interior angles are congruent.
Same-Side Interior Angles Theorem
O If a transversal intersects two parallel lines, then same-side interior angles are supplementary.
Pairs that are congruent
What’s the BIG idea?O When you see two parallel lines and a
transversal, and you know the measure of one angle, you can find the measure of ALL of the angles.
Example #1Find the measure of each angle. Which
theorem or postulate justifies each answer?
Example #2Find the values of x and y.
Example #3
Find the values of x and y.
Two-Column Proof
Proof Example #1Proof of Alt. Interior Theorem
Proof Example #2
Tips for SuccessO Highlight the parallel lines.O Know your angle vocabulary!O Know your angle pairs…
O Alt. Interior, Corresponding, Alt. Exterior, Vertical Angles are CONGRUENT
O Same-side interior angles are SUPPLEMENTARY
O Be on the lookout for vertical angles!
HOMEWORKO Page 118 #1-8, #11-17, #30O TIP: Redraw the figures and highlight
the parallel lines to help you “see” the angle pairs.