Which pair of slopes could represent perpendicular lines?

1/7, 7
1/2, 2/4
-3/4, 4/3
1/3, 1/3

Question

Which pair of slopes could represent perpendicular lines?

1/7, 7
1/2, 2/4
-3/4, 4/3
1/3, 1/3

jim_thompson5910 · Answer

any pairs of slopes that multiply to -1 will represent perpendicular lines

cloverracer · Answer

Doesn't it have something to do with a reciprocal? So far I think it is B or C. I am leaning towards C because of the reciprocal thing.

jim_thompson5910 · Answer

that's another way to think of it

if you have one slope of 7 = 7/1, then you flip the fraction and flip the sign to get -1/7

some books or teachers refer to this as "negative reciprocal"

jim_thompson5910 · Answer

another example

original slope: 2/9

flip the fraction 2/9 ---> 9/2

flip the sign: 9/2 ---> -9/2

So 2/9 and -9/2 are perpendicular slopes

cloverracer · Answer

Oh, yeah I see. That looks the same as C, since it is -3/4 and 4/3

jim_thompson5910 · Answer

correct

cloverracer · Answer

Thanks for the help!

jim_thompson5910 · Answer

np