1. Determining if Lines are Parallel or Perpendicular Parallel linesPerpendicular lines Slopes are the same Slopes are opposite reciprocals (assume no vertical lines) Recall the relationships between the slopes of parallel and perpendicular lines:

2. Example 1: For the pair of lines, determine if their graphs are parallel, perpendicular, or neither. Determine the slope of each line: Since the slopes are the same, the lines are parallel.

3. Example 2: For the pair of lines, determine if their graphs are parallel, perpendicular, or neither. Write each equation in slope intercept form:

4. Line 1:

5. Line 2:

6. Determine the slope of each line: Since the slopes are opposite reciprocals, the lines are perpendicular.

7. Example 3: For the pair of lines, determine if their graphs are parallel, perpendicular, or neither. This equation has the form of a vertical line. This equation has the form of a horizontal line. The lines are perpendicular.