Introduction to Parallel and Perpendicular Lines

Parallel and Perpendicular Lines

By Scott Donnelly

Multiple Choice

What is slope intercept form?

• $$y=mx+b$$  

• $$m=\frac{rise}{run}$$  

• $$y-y_1=m\left(x-x_1\right)$$  

Multiple Choice

In slope intercept form, $$y=mx+b$$  

which variable is the slope?

• b

• mx

• m

• y

Parallel or Perpendicular Lines

Parallel or Perpendicualar Lines

Parallel or Perpendicular Lines

1. ​Get equation in slope intercept form.

2. Determine the slope.

3. If given 2 points find the slope or look at the 2 slopes​ and determine if they are equal or multiply to give -1.

Perpendicular Line

​Parallel Line

Parallel or Perpendicular

Multiple Choice

Which line would be parallel to $$y=-\frac{1}{2}x+4$$  

• $$y=\frac{1}{2}x+1$$  

• $$y=2x-4$$  

• $$y=-2x+7$$  

• $$y=-\frac{1}{2}x$$  

Multiple Choice

Which line would be perpendicular to $$y=-\frac{1}{2}x+4$$  

• $$y=\frac{1}{2}x+1$$  

• $$y=2x-4$$  

• $$y=-2x+7$$  

• $$y=-\frac{1}{2}x$$  

Multiple Choice

Are these 2 lines parallel, perpendicular or neither?

$$y=4x-4$$  

$$y=-4x+2$$  

• Parallel

• Perpendicular

• Neither

Multiple Choice

Are these 2 lines parallel, perpendicular or neither?

$$y=-\frac{2}{3}x+7$$  

$$y=\frac{3}{2}x-7$$  

• Parallel

• Perpendicular

• Neither

Multiple Choice

Are these 2 lines parallel, perpendicular or neither?

$$y=5x-4$$  

$$y=5x+7$$  

• Parallel

• Perpendicular

• Neither

Perpendicular Line

​Parallel Line

Parallel or Perpendicular

​Perpendicular

​Parallel

Writing Equation Through Point

Write Line Parallel

​Example

Draw

Write the equation of a line parallel to line below and goes through (1,3) $$y=-5x+4$$

Write Line Perpendicular

​Example

Draw

Write the equation of a line parallel to line below and goes through (-3,7) $$y=3x+4$$