1. PARALLEL LINES Linear Equations

2. I can find the equation of a line parallel to a given line passing through a given point. Essential Question: Do you use the x- or y- coordinate to find the equation parallel to x=8? How do you know?

3. PARALLEL LINES ARE LINES IN THE SAME PLANE THAT NEVER INTERSECT  The symbol for parallel lines is  Sketch a graph of two parallel lines.  You can determine if two lines are parallel by comparing the slopes and y-intercepts of the lines.

4. WHEN WILL LINES BE PARALLEL?  Non-vertical and non-horizontal lines will be parallel when they have the same slope and different y-intercepts.  Example:y=2x+1 is parallel to y=2x+7  Vertical lines are parallel when they have different x-intercepts. (Remember all vertical lines have an undefined slope)  Example: x=4 is parallel to x=9  Horizontal Lines will be parallel when they have different y-intercepts. (Remember all horizontal lines have a zero slope)  Example:y=-1 is parallel to y=15

5. STEPS TO WRITE EQUATION A LINE PARALLEL TO A NON- VERTICAL, NON-HORIZONTAL LINE PASSING THROUGH A GIVEN POINT. EXAMPLE: FIND THE EQUATION OF A LINE PARALLEL TO Y=3X+1 THAT PASSES THROUGH THE POINT (2, 1) 1. Find the slope of the given line. This will be the slope of your new line. 2.Determine x and y from the given point. 3. Substitute m, x and y into the equation y=mx+b and solve for b. 4. Substitute your m and b into y=mx+b m=3. x=2 and y=1 1=3(2)+b 1=6+b -5=b y=3x-5

6. STEPS TO WRITE THE EQUATION OF THE LINE PARALLEL TO A VERTICAL LINE EXAMPLE: FIND THE EQUATION OF A LINE PARALLEL TO X=5 THAT PASSES THROUGH (2, 1) 1. Determine the x-coordinate of the point 2. Write the equation of the line as x=_____ The x-coordinate is 2 x=2 is the equation of the line

7. STEPS TO FIND THE EQUATION OF A LINE PARALLEL TO A HORIZONTAL LINE PASSING THROUGH A GIVEN POINT EXAMPLE: FIND THE EQUATION OF THE LINE PARALLEL TO Y=3 THAT PASSES THROUGH THE POINT (9, 0) 1. Find the y-coordinate of the given point. 2. Write the equation of the line as y=_______ The y-coordinate is 0 The equation of the line is y=0