Warm Up Complete the handout and turn in when finished
Practice with Supplemental Angles Find the missing Angle: Find x:
Let’s look at a pair of parallel lines cut by a transversal. What kind of angles are 1 and 2? Corresponding If we TRANSLATE the bottom line upward, what do we notice? 1 Ask what translate means! It’s the same angles 2
Properties of Parallel Lines
Let’s look further… Suppose mb = 60 Use what you know about vertical, supplementary, and corresponding angles to find the measures of all the other angles Can we make any conclusions?
More Postulates When a transversal intersects two parallel lines, we have two other interesting angle properties
II. This is easy to remember because we know about vertical angles and corresponding angles!
III. This is easy because we know supp (linear pair) and corr
Two options for angles with parallel lines and transversals Either the two angles are congruent (Vertical angles, Alternate, Corresponding) or they add to 180 (same side interior, same side exterior, create straight line)
Find x
Create equations and solve
Group Work Use the properties of parallel lines cut by a transversal to determine the indicated angles. http://www.mathsisfun.com/geometry/parallel- lines.html
More Definitions Bisect – to divide a line/angle/shape into two equal parts Perpendicular Bisector - A line which cuts a line segment into two equal parts at a right angle (90°).
Homework Set up equations using the properties of parallel lines cut by a transversal to solve.