1. Perpendicular Lines Sec 3.7 Goals: To identify perpendicular lines using slope To write equations of perpendicular lines

2. Slope

3. Comparing Slopes of Lines In a coordinate plane, two nonvertical lines are perpendicular if and only if the product of their slopes is -1. Vertical and horizontal lines are perpendicular.

4. Examples Decide whether

5. Examples Decide whether the lines are perpendicular.

6. Writing Equations Find an equation of a line passing through (3,1) and perpendicular to line r. 1. Find the slope of a line that is perpendicular to line “r”. 3. Plug and b into 2. Use and the point given to find b.

7. Students 1. Decide whether the lines are perpendicular. 2. Find an equation passing through (2,-2) and perpendicular to 3. Are the lines with the following points passing through them perpendicular? Line l (0,7) and (5,2) Line t (9,6)and (4,1)