Ch 6'5

1
Ch 6.5

• Writing Parallel Perpendicular Equations

2
Writing Parallel Perpendicular Equations

• Writing a line parallel to the given equation
• Find slope of given equation (rewrite in
  slope-int if nec.)
• Take the slope the given point plug into
  point-slope form. y-y1m(x-x1)
• Re write equation to Slope-Int form.

• Ex. y 2/7x 4 pt (2,-3)
• m 2/7 x1,y1
• y 3 2/7(x - 2)
• y 3 2/7x - 4/7
• -3 -3
• y 2/7x - 25/7 or
• y 2/7 x- 3.6

3

• Write a Parallel line
• Ex. 3x 4y 12 pt(5,1) (chg to slope-int)
  or use m -A/B
• -3x -3x x1,y1
• 4y -3x 12 y -3x 3
• 4 4 4 4
• m -3/4 pt(5,1) y 1 -3/4(x - 5)
  (pt-slope form)
• y 1 -3/4(x - 5) distribute
• (rewrite in slope-int form)
• y - 1 -3/4x 15/4
• 1 1
• y -3/4x 19/4

4
TRY SOME

• Write a line parallel to the given equations
• 1. y 5/2x 4 pt(-2, 3) 2. 4x 3y 36
  pt(-1, 0)

5

• Writing a line perpendicular to the given
  equation
• Follow the same steps for writing parallel lines
  except when you find the slope of the given line
  change it to the negative (oppo) recip.

• Ex. y 2/5x 9 pt(-3, 4)
• x1,y1
• m 2/5 chg to -5/2
• y 4 -5/2(x 3)
• y 4 -5/2x - 15/2
• 4 4
• y -5/2x - 7/2

6

• Ex. Write a Perpendicular Line
• 3x 5y 7 pt(-1, 2) or use m -A/B
• -3x -3x x1,y1
• 5y -3x 7 5 5 5
• y -3/5x 7/5
• m -3/5 chg 5/3 pt(-1,2)
• y 2 5/3(x1) (pt-slope form)
• y 2 5/3x 5/3 (rewrite in slope-int form)
• 2 2
• y 5/3x 11/3

7
TRY SOME

• Write a line perpendicular to the given
  equations
• 1. y -2x 7 pt(6, 2) 2. 2x y 2
  pt(-4, -3)