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Writing the Equation of a Perpendicular Line 9 Views


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Description:

What could be the equation of a line perpendicular to the line shown?


Transcript

00:02

Okay math people Here we go Another graph Right What

00:04

could be the equation of the line perpendicular to the

00:08

line shown All right so let's stare at that perfect

00:15

ninety degree angle to the line right there Yeah we're

00:18

putting down the sharpie The computer based ccs fire won't

00:21

give you points for defacing school property Perpendicular lines have

00:24

slope with the opposite signs i'ii won will be negative

00:28

The other positive and the values of their slopes will

00:31

be reciprocal Sze Well well positive slopes rise up on

00:35

the y axis as x values increase like goes up

00:39

like that and there's a negative slope of those go

00:41

downwards as x values go up we can make our

00:44

mathematical lives a little easier by eliminating a few of

00:46

these choices right off the bat Since we're looking for

00:49

a line that's perpendicular to the one in the graph

00:51

it happens to have a positive slope so we can

00:54

narrow down the answers to the two with negative slopes

00:57

Right it's got to be either a or b All

00:58

we need to do now is find the slope of

01:00

our graph and take its negative reciprocal Well if we

01:03

started the y you nurse after zero two right there

01:06

and head to the point one five when we move

01:09

up three units and go to the right One unit

01:12

right there Well slope is the ratio of vertical change

01:14

Toe horizontal change so well that's rise of iran and

01:17

the three over one perpendicular lines then have slopes that

01:21

air negative reciprocal sze of each other So a line

01:24

with a slope perpendicular to this one must have a

01:27

slope of negative one third Don't forget the negative in

01:31

there Yeah so it's going to be on the y

01:33

equals mx plus b format It'll be why equals negative

01:37

one third act's minus four so that's it The answer 00:01:40.244 --> [endTime] is b

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