Parallel and Perpendicular Lines

Topics for Today:

The slope of two lines can produce a special relationship between those lines.  Two such relationship are parallel lines and perpendicular lines.  Parallel lines exist in the same plane but will never intersect, and they always have the same slope.  Perpendicular lines are special because when they intersect, the lines form 90° angles.  The slopes of perpendicular lines are negative reciprocals of each other, and when those slopes are multiplied together, the result is -1.

We will be analyzing the slopes of two lines to determine if either relationship exists, and we will be deducing linear equations from a given point that is either parallel or perpendicular to the given line.

Parallel and perpendicular lines are always determined by the relationship of their slopes!

Vocabulary: parallel lines, perpendicular lines, negative reciprocal

Sections Covered in Textbook:

6-5: Parallel and Perpendicular Lines (pages 311 - 316)

Resources & Tutorials:

1) How do you find the slope of a line if you have a parallel line?
2)  How do you write an equation of a line in slope-intercept form if you have one point and a parallel line?
3) How do you find the slope of a line if you have a perpendicular line?
4) How do you write an equation of a line in slope-intercept form if you have one point and a perpendicular line?
5) How to tell if lines are parallel, perpendicular, or neither.

6) Parallel and Perpendicular Lines Class notes