# MPM2D Parallel, Perpendicular, and Graphing 2016-09-14

We reviewed parallel and perpendicular lines:

Parallel Lines Perpendicular Lines
Never touch, unless they’re the same line Touch at exactly one point
Travel in the same directions Travel in “opposite” directions
Have the same slope ($m_1 = m_2$) Have slopes that are negative reciprocals ($m_1=-\frac{1}{m_2}$)

Remember that horizontal lines have a slope of 0, and vertical lines have undefined slope.

Then we graphed three lines using three strategies: Table of Values (ToV), Intercepts, and Slope-y-Intercept ($m$ & $b$). Here are the notes we took:

graphing-strategies-1

graphing-strategies-2

Homework for tonight is to complete Page 17 #7, 8ac, 9ac.

If you need more graph paper you can find some at http://www.printfreegraphpaper.com/ (I recommend the 1/4″ or the 10mm Cartesian paper for most purposes).