10/10/2013
Warm Up:
Lesson 3.5:
• On your own paper, please do the following:
p. 161: #9
1. Warm Up/Homework
2. Constructing Parallel Lines
Constructing Parallel Lines:
• On page 163, there are instructions for
constructing parallel lines by using patty
paper. Please follow the directions, construct
parallel lines and then staple the patty paper
into your notes.
Constructing Parallel Lines:
• Now we are going to construct a line parallel
to another line through a point not on the
line. Follow the steps as you watch me
demonstrate. We will add these to your
Learning Targets Handout.
Steps for Parallel Lines Construction:
1.
2.
3.
4.
5.
6.
7.
8.
Draw line “b” and then a point “p” not on line b.
Draw a transversal that goes through p and intersects line b. Label
the intersection a.
Draw a circle (or an arc) that has a center at a and intersects the
transversal and line I.
Without changing the radius, draw a congruent circle (or draw an
arc) with center p.
Use your compass to measure the distance from where circle a
intersects the transversal and line b.
Now, use your compass on circle p to mark off the same distance
starting from the transversal intersection. Label the point q.
Draw a line through points p and q.
ll4
Group Practice:
• R164:#4
• When you finish, write the formula for slope:
m=
1
10/10/2013
Slopes of Parallel Lines:
Slopes of Perpendicular Lines:
Parallel Slope Property na coordinate plane, two distinct
lines are parallel if and only if their slopes are
or they are both vertical lines,
Perpendicular Slope Property— In a coordinate plane, two
non-vertical lines are perpendicular if and only if their slopes
are
—
Example #1:
Given the following points, are AB and ö
parallel, perpendicular or neither?
A(—15, —6), B(6, 8), C(4, —2), D(—4, 10)
Example #2:
Find the slope of each side and then determine whether each
figure isa trapezoid, a parallelogram, a rectangle, or just an
ordinaryquadrilateral.
Homework:
• R 164-165: 2, 5, 7, 8, 14-16
• P. 169: 1, 2, 9
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