2 Perpendicular LinesA line is perpendicular to another if it meets or crosses at right angles (90°). For instance, a horizontal and a vertical line are perpendicular lines.
3 Slopes of Perpendicular Lines Complete the following assuming Line A and Line B are perpendicular.Make Line A have a slope ofWhat is the slope of Line B (the line perpendicular to Line A)?ABABABAB-3223
4 Slopes of Perpendicular Lines Two lines are perpendicular if their slopes are opposite reciprocals of each other. In other words, if the slope of a line is then the perpendicular line has a slope ofExample: What is the slope of a line perpendicular to each equation below.
5 Note: The y-intercepts Normally are Not the Same 99.9% of the time, if two lines are parallel or perpendicular, they will NOT have the same y-intercept. (In fact, only RARELY do perpendicular lines share a y-intercept. If lines with the same slope have the same y-intercept, the lines coincide and are not parallel.)
6 Example Find the y-intercept. Algebraically find the equation of the line that goes through the point (2,3) and is perpendicular to y = -4x – 2.This y-intercept does not matter.Find the y-intercept.Use Slope-Intercept Form:The slope is ¼A point on the graph is x=2 and y=-3The equation now has one distinct variable. Solve it.Substitute back into Slope-Intercept Form: