Check my answer please! Medal!
Triangle ABC has been rotated 90° to create triangle DEF. Using the image below, prove that perpendicular lines have opposite and reciprocal slopes. You must show all of your work to receive credit.

Question

Check my answer please! Medal!
Triangle ABC has been rotated 90° to create triangle DEF. Using the image below, prove that perpendicular lines have opposite and reciprocal slopes. You must show all of your work to receive credit.

anonymous · Answer

Answer:
B(4,5) C(1,1) E(5,-4) F(1,-1)
Perpendicular lines require two lines to have slopes reciprocal to each other.

The slope of BC and the slope of EF should be reciprocal to each other to make them perpendicular.
y2 - y1
--------- = slope
x2 - x1
Slope of BC
1 - 5          -4
--------- =  -----
1 - 4          -3
Slope of EF
-1 - - 4       -3
--------- =  -----
1 - 5           -4
So -4/-3 and -3/-4 means its not opposite and reciprocal slopes

anonymous · Answer

@tkhunny

anonymous · Answer

@hartnn

anonymous · Answer

@cwrw238

daniel_chernioglo · Answer

Is there a graph that came with this?

anonymous · Answer

attachment

anonymous · Answer

do you know this?

daniel_chernioglo · Answer

Well i do know some of it

tkhunny · Answer

-1 - (-4) = -1 + 4 = +3

Other than that, it looks good.

daniel_chernioglo · Answer

here is a link to the same question that was answered

daniel_chernioglo · Answer

http://openstudy.com/study#/updates/53bdacf2e4b0bbb79bdbe3d9

anonymous · Answer

oh right right
So -4/-3 and 3/-4 means its not opposite and reciprocal slopes? therefore not perpendicular?

daniel_chernioglo · Answer

I think that they have a different answer than yours.
They have 4/3 and -3/4

anonymous · Answer

yeah but i dont understand how they got 4/3 and 3/4

anonymous · Answer

i mean -4/-3 and 4/3

anonymous · Answer

the 4/3 is incorrect

daniel_chernioglo · Answer

yes im not sure about that part

anonymous · Answer

i think its not perpendicular, and they got it wrong

daniel_chernioglo · Answer

oh wait

daniel_chernioglo · Answer

You had only one mistake

daniel_chernioglo · Answer

Just like @tkhunny told you,
-1 - (-4) = -1 + 4 = +3

anonymous · Answer

right 3/-4 instead of -3/-4

daniel_chernioglo · Answer

so you would have: -4/-3 and 3/-4

daniel_chernioglo · Answer

yup

anonymous · Answer

so is that the opposite reciprocal of -4/-3?

anonymous · Answer

i think the opposite reciprocal of -4/-3 should be 3/4 right?

anonymous · Answer

nvm check this out
If you have two straight lines on a graph that are perpendicular (they meet at right angles), then the gradient (or slope) of one is always the opposite reciprocal of the other. So if the gradient of one line is 4/3, then the gradient of the other is -3/4. Here we have inverted the fraction (4/3 becomes 3/4) to find the reciprocal, and changed the sign (3/4 becomes -3/4) to make it the opposite reciprocal.

anonymous · Answer

so opposite reciprocal of -4/-3 would be
-4/-3 --> 4/3 --> -4/3

daniel_chernioglo · Answer

Yes i think so

anonymous · Answer

ok thanks I think i know what to answer know

daniel_chernioglo · Answer

Sorry this was so confusing

daniel_chernioglo · Answer

Thank you for the medal :)

anonymous · Answer

i know right xD

anonymous · Answer

and your welcome