Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2018-02-03 01:56:17

Hannibal lecter
Member
Registered: 2016-02-11
Posts: 222
Website

can two lines be perpendicular and parallel at the same time?

Hi,

can two lines be perpendicular and parallel at the same time?

if not...then what is mean the following ? :-

Find equations for the lines through the point (1,5) that are parallel to and perpendicular to the lines the equation y + 4x =7


if the answer is not how can that be " that are parallel to and perpendicular to .. " ???


Wisdom is a tree which grows in the heart and fruits on the tongue

Offline

#2 2018-02-03 02:01:37

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,188
Website

Re: can two lines be perpendicular and parallel at the same time?

No, you need to find two lines: one which is parallel to y = 4x + 7, and one which is perpendicular to it, each of which pass through (1,5).

Offline

#3 2018-02-03 05:38:25

Hannibal lecter
Member
Registered: 2016-02-11
Posts: 222
Website

Re: can two lines be perpendicular and parallel at the same time?

how can that be in a graph drawing
I know the slop is 1/4


Wisdom is a tree which grows in the heart and fruits on the tongue

Offline

#4 2018-02-03 06:15:40

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,188
Website

Re: can two lines be perpendicular and parallel at the same time?

Let's start with finding the parallel line through (1,5).

Can you write down a line which is parallel to y = 4x + 7?

Offline

#5 2018-02-03 06:56:19

Hannibal lecter
Member
Registered: 2016-02-11
Posts: 222
Website

Re: can two lines be perpendicular and parallel at the same time?

it's

y= 1 +4x right?


Wisdom is a tree which grows in the heart and fruits on the tongue

Offline

#6 2018-02-03 07:59:28

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,188
Website

Re: can two lines be perpendicular and parallel at the same time?

Correct! And you can check your answer by substituting x = 1 into your answer to get y = 5.

Now for the perpendicular line passing through (1,5). The line y = 4x + 7 has a gradient of 4. What is the gradient of the perpendicular line?

Offline

#7 2018-02-03 11:26:58

Hannibal lecter
Member
Registered: 2016-02-11
Posts: 222
Website

Re: can two lines be perpendicular and parallel at the same time?

I know it's -1/4

what after that?


Wisdom is a tree which grows in the heart and fruits on the tongue

Offline

#8 2018-02-03 20:42:40

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,188
Website

Re: can two lines be perpendicular and parallel at the same time?

Yes, so if the perpendicular line has a gradient of
, then the line must be of the form
. Given that the line passes through
, can you find the value of
?

Offline

#9 2018-02-03 22:58:05

Hannibal lecter
Member
Registered: 2016-02-11
Posts: 222
Website

Re: can two lines be perpendicular and parallel at the same time?

I think It's -1/-4  which gives 1/4 positive not negative I think my answer was not correct

so the line is y=0.25x + 4.75


Wisdom is a tree which grows in the heart and fruits on the tongue

Offline

#10 2018-02-03 23:05:47

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,188
Website

Re: can two lines be perpendicular and parallel at the same time?

No, it's -1/4: the gradient of a line and the gradient of the line perpendicular to it must multiply to make -1.

Offline

#11 2018-02-04 00:22:43

Hannibal lecter
Member
Registered: 2016-02-11
Posts: 222
Website

Re: can two lines be perpendicular and parallel at the same time?

sorry but the orignal line was y = -4x + 7   the slop not positive I'm talking about this case

but thanks anyway I solved  all the question about that field


Wisdom is a tree which grows in the heart and fruits on the tongue

Offline

#12 2018-02-04 00:56:51

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,188
Website

Re: can two lines be perpendicular and parallel at the same time?

Ah, I see -- my apologies, I misread the original equation. In that case, you are completely correct.

Offline

Board footer

Powered by FluxBB