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All You Need to Know about Slopes of Parallel and Perpendicular Lines 2753 Views


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Description:

So many parallel and perpendicular lines all over the place, and none of them have been labeled. Which begs the question: whose lines are they, anyway?

Language:
English Language

Transcript

00:04

Slopes of parallel and perpendicular lines, a la Shmoop. [title page]

00:08

Two magician's apprentices have turned their master into a bear--which is a problem, because [magician turns into bear]

00:13

he's an angry bear. [bear chases kids]

00:15

Help them figure out what went wrong by calculating whether the slopes of their magic rays were

00:20

parallel or perpendicular.

00:22

The equations of their magic rays are: y=3x+4 and y=3x+10. [equations shown]

00:30

Fortunately, these equations are already set up in slope-intercept form (y=mx+b, where [equations on slopes]

00:38

m is the slope). [slope-intercept form demonstrated]

00:41

That means that the slope in each equation is 3.

00:45

According to the Magician's Apprentice Handbook, "If two lines are perpendicular, their slopes [handbook opens]

00:50

are negative reciprocals of each other."

00:53

Negative reciprocals, when multiplied together, equal -1. [negative reciprocals defined]

00:58

3 x -1/3 = -1, so if one of the two equations had a slope of -1/3, then these two equations

01:08

would be perpendicular to each other. [perpendicular lines explained]

01:10

If two lines are parallel, their slopes are the same. [parallel lines defined]

01:14

Since we know each equation has a slope of 3, their slopes are parallel.

01:19

Oh, here it is, page 32... [handbook opens]

01:22

"Parallel magic rays deployed at the same time result in... bear."

01:27

Magical antidote?

01:28

Get rid of the evidence. [kids run from bear]

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