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Honors Geometry Section 3.8 Lines in the Coordinate Plane. Objectives: 1. Find the slope of the line through 2 points. 2. Find the slope of a line parallel to a given line. 3. Find the slope of a line perpendicular to a given line . 4. Write the equation of a line.
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Objectives:1. Find the slope of the line through 2 points.2. Find the slope of a line parallel to a given line.3. Find the slope of a line perpendicular to a given line.4. Write the equation of a line.
The slope of a line is a ratio that indicates how a line rises or falls from left to right.
The slope of a nonvertical line that contains the points is equal to the ratio
When graphing, it is helpful to think of slope as rise over run.
Examples: Find the slope of the line through the given points.
Two nonvertical lines are parallel ifftheir slopes are equal.Note: Vertical lines will be parallel.
Two nonvertical lines are perpendicular ifftheir slopes are opposite reciprocals.Note: A horizontal line and a vertical line are perpendicular. change the sign flip the fraction
There are two forms for an equation of a line with which you should be familiar.Slope-intercept form:Point-slope form:
Example: Write an equation in point-slope form for the line through the point (3, -5) with a slope of .
Example: Write an equation, in slope-intercept form, for the line through the point (12, 5) that will be perpendicular to the line .
Example: Write an equation, in slope-intercept form, for the line through the points (2, -5) and (4, 2).