Graphing Parallel and Perp Lines

Graphing Parallel and Perp Lines and Writing their Equations

​

Poll

When you have an Asynchronous day on Monday 10/19, will you?

• Get up on normal schedule and keep to my regular schedule

• Get up at normal time and just work as hard as I can to get done early

• Sleep in but get everything done during the day

• Sleep in late and get most work done but maybe not all

Multiple Choice

Choose the graph that is parallel to x=0 and goes through (2,5)

Remember VUX

• Vertical (up and down)

• slope m=undefined (up and down)

• x=# is the equation

• line intersects the x-axis

Multiple Choice

What is the equation of the parallel line (RED)?

• x=2

• x=5

• y=2

• y=5

Multiple Choice

Choose the graph that is perpendicular to x=0 and goes through (2,5)

Remember HOY

• Horizontal (left and right)

• slope m=0 (left and right)

• y=# is the equation

• line intersects the y-axis

Multiple Choice

What is the equation of the perpendicular line (RED)?

• x=2

• x=5

• y=2

• y=5

Multiple Choice

Choose the graph that is parallel to 

 $y=\frac{9}{2}x-3$  and goes through (3,4)

Write the equation of the line in Point-Slope Form

• y-y1=m(x-x1)

• (x1,y1) swap places and change signs as you plug them in

• for Parallel Lines keep the same slope, m=

• for Perpendicular Lines change the slope to opposite and reciprocal, m=

Multiple Choice

What is the equation in Point-Slope Form of the RED line that is parallel to $y=\frac{9}{2}x-3$  

and goes through (3,4)

•  $y-3=\frac{9}{2}\left(x-4\right)$  
  

•  $y-3=-\frac{2}{9}\left(x-3\right)$  

•  $y-4=\frac{9}{2}\left(x-3\right)$  
  

•  $y-4=-\frac{2}{9}\left(x-3\right)$  
  

Write the equation in Slope-Intercept Form

• starting with your PSF y-y1=m(x-x1)

• distribute the slope

• cancel the y1 to the back of the equation

• 
  

Multiple Choice

 $y-4=\frac{9}{2}\left(x-3\right)$  Convert into Slope Intercept Form

•  $y=\frac{9}{2}x-1$  

•  $y=\frac{9}{2}x-\frac{1}{2}$  

•  $y=9/2x-5$  

•  $y=\frac{9}{2}x-\frac{19}{2}$  

Multiple Choice

Choose the graph that is perpendicular to 

 $y=\frac{9}{2}x-3$  and goes through (3,4)

Multiple Choice

What is the equation in Point-Slope Form of the RED line that is perpendicular to $y=\frac{9}{2}x-3$  

and goes through (3,4)

•  $y-3=\frac{9}{2}\left(x-4\right)$  
  

•  $y-3=-\frac{2}{9}\left(x-3\right)$  

•  $y-4=\frac{9}{2}\left(x-3\right)$  
  

•  $y-4=-\frac{2}{9}\left(x-3\right)$  
  

Multiple Choice

 $y-4=-\frac{2}{9}\left(x-3\right)$  Convert into Slope Intercept Form

•  $y=-\frac{2}{9}x+2$  
  

•  $y=-\frac{2}{9}x+\frac{11}{3}$  
  

•  $y=-\frac{2}{9}x+\frac{14}{3}$  
  

•  $y=-\frac{2}{9}x+10$