It’s What’s Going On!

RecallRecall

y = mx + b is the equation of a line

m is the value of the slope of a line (rise over run)

b is the y-intercept

m = 1__2

b = 0

Parallel Lines: LessonParallel Lines: Lesson

Parallel lines have the same slope or m value

Parallel lines are always the same distance apart

Parallel lines move in the same direction and never meet Same distance

throughout

Parallel Lines: ApplicationParallel Lines: Application

Graph the following lines:

y=4x-3 and y=4x-1 What is the

relationship between these lines?

Graph two more lines with this relationship y = 4x-1 y = 4x-3

Parallel Lines: ApplicationParallel Lines: Application

Graph the line y=2x+1 Graph a line parallel to

this line with a y-intercept at 4

y = 2x+1y-intercept

Perpendicular Lines: LessonPerpendicular Lines: Lesson

Perpendicular lines intersect each other at 90° angles

Perpendicular lines have slopes that are negative reciprocals of each other.

Perpendicular Lines: Perpendicular Lines: ApplicationApplication

Graph the following lines:

y=1x+1 and y=-2x+1

What is the relationship between these lines?

Graph 2 more lines with this relationship.

_2

y = 1x + 1y = -2x + 1__2

Perpendicular Lines: Perpendicular Lines: ApplicationApplication

Graph the line y=3x + 2

Graph a line

perpendicular to this line with a y-intercept at 3.

4_

y = 3x + 2_4

Horizontal Lines IntroductionHorizontal Lines Introduction

Lines that are horizontal have a slope of zero. They have "run", but no "rise". The rise/run formula for slope always yields zero since

Horizontal Lines: LessonHorizontal Lines: Lesson

Horizontal lines have no x-intercept

They are parallel to the x-axis

If (0,1) is y-intercept of a horizontal line, then the equation of the line is y=1

Have a undefined slope

Horizontal Lines: ExampleHorizontal Lines: Example

Remember, horizontal lines are parallel to the x-axis.

Example 1: y=2 Example 2: y=4

Horizontal Lines: ApplicationHorizontal Lines: Application

Graph the following lines:

y=3 y=1 y=-2 y=-3

Click the mouse to show answers

Vertical Lines IntroductionVertical Lines Introduction

Lines that are vertical have no slope (it does not exist).  They have "rise", but no "run".  The rise/run formula for slope always has a zero denominator and is undefined.

Vertical Lines: LessonVertical Lines: Lesson

Vertical lines have no y-intercept

They are parallel to the y-axis

If (1,0) is x-intercept of a vertical line, then the equation of the line is x=1

Have a undefined slope

Vertical Lines: ExampleVertical Lines: Example

Remember, vertical lines are parallel to the y-axis.

Example 1: x=-2 Example 2: x=1

Vertical Lines: ApplicationVertical Lines: Application

Graph the following lines:

x=2 x=-3 x=4 x=1

Click the mouse to show answers

Horizontal & Vertical Horizontal & Vertical ReloadedReloaded

Graph the following lines:

x=2 y=3

You are now a master of Horizontal and Vertical lines

Web-sites to visit:Web-sites to visit:

http://www.math.com/school/subject3/lessons/S3U1L3GL.html

http://www.sci.wsu.edu/~kentler/Fall97_101/nojs/Chapter3/section2.html

http://regentsprep.org/Regents/math/line-eq/EqLines.htm

http://www.hoxie.org/math/algebra/stline1.htm

Horizontal and Vertical Lines

Parallel and Perpendicular Lines