# ACT Aspire Math: Writing the Equation of a Perpendicular Line

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

ACT Aspire | Math |

ACT Aspire Math | Geometry |

Math | Geometry |

Product Type | ACT Aspire |

Test Prep | ACT Aspire ACT Aspire Math |

### Transcript

give you points for defacing school property Perpendicular lines have

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

The other positive and the values of their slopes will

be reciprocal Sze Well well positive slopes rise up on

the y axis as x values increase like goes up

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

downwards as x values go up we can make our

mathematical lives a little easier by eliminating a few of

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

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

it happens to have a positive slope so we can

narrow down the answers to the two with negative slopes

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

we need to do now is find the slope of

our graph and take its negative reciprocal Well if we

started the y you nurse after zero two right there

and head to the point one five when we move

up three units and go to the right One unit

right there Well slope is the ratio of vertical change

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

the three over one perpendicular lines then have slopes that

air negative reciprocal sze of each other So a line

with a slope perpendicular to this one must have a

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

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

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

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