1. Section 5 – Writing Equations of Parallel and Perpendicular Lines
Chapter 1
Section 5 – Writing Equations of Parallel and Perpendicular Lines

2. Parallel Lines
If two or more lines are parallel, then they have the same slope.
If two or more equations are the same, then the lines coincide.

3. Parallel, Coincide, or Neither?
Answer the following examples by saying the lines are either parallel, coincide, or neither.
EX 1: 3x-4y=12 and 9x-12y=72
EX 2: 15x+12y=36 and 5x+4y=12
EX 3: .5x-2y=8 and .25x-y=4

4. Writing Equations
For the following examples, write the equation in slope-intercept form of the line that goes through the given point and is PARALLEL to the given line.
EX 4: P(4,-7) 2x-5y+8=0
EX 5: R(-6,-1) 4x+3y-7=0

5. Perpendicular Lines
If two lines are perpendicular, then their slopes are opposite reciprocals.
For example, if the slope of one line is -2, then a line perpendicular to it has a slope of ½.

6. Writing More Equations
For the following two examples, write an equation of a line that is perpendicular to the given line and goes through the given point.
EX 6: S(3,4) y=6x-2
EX 7: T(-2,-5) 3y-4=2x

7. Assignment 1.5
Chapter 1, Section 5 pgs #6-30 evens