Title: Geometry: Parallel and Perpendicular Lines
1Lesson 5-6
- Geometry Parallel and Perpendicular Lines
2Transparency 6
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3Transparency 6a
4Objectives
- Locate points on the coordinate plane
- Graph points on a coordinate plane
- Write an equation of the line that passes through
a given point, parallel to a given line - Write an equation of the line that passes through
a given point, perpendicular to a given line
5Vocabulary
- Coordinate plane an x-y grid with axes as
reference lines - Quadrant the axes divide the coordinate plane
into 4 regions or quadrants - Graph is a plot of an ordered pair (x,y) on the
coordinate plane - Parallel lines lines in the same plane that
never intersect and have the same slope - Perpendicular lines lines that meet to form
right angles
6x-y Coordinate Plane
Quadrants
Point Plotting
I
II
up 7
left 4
right 5
III
IV
down 8
(x, y) (-4, 7) (5, -8) x left or
right y up or down
7Example 1
8Example 1 cont
9Example 2
Step 1 Find the slope of the given line.
10Example 2 cont
Step 3 Use the point-slope form to find the
equation.
11Example 2 cont
12Example 3
13Example 3 cont
Step 2 The slope of the given line is -5/2. So,
the slope of the line perpendicular to this line
is the opposite reciprocal of -5/2 or 2/5.
Step 3 Substitute the slope and the given point
into the point-slope form of a linear equation.
Then write the equation in slope-intercept form.
14Summary Homework
- Summary
- Two nonvertical lines are parallel if they have
the same slope - Two nonvertical lines are perpendicular if the
product of their slopes is -1 - Homework
- Pg 296 14-40 even