# help with straights in space

#### john445

##### New member
1 - How do you find a straight perpendicular to S and passes through point A?
2 - How to find the distance between any straight S and any point A?
3 - And how to find the symmetric of A in relation to S?

#### pka

##### Elite Member
What in the world are straights in space?

#### john445

##### New member
What in the world are straights in space?
i mean, lines in space R^3

#### pka

##### Elite Member
i mean, lines in space R^3

1 - How do you find a straight perpendicular to S and passes through point A?
2 - How to find the distance between any straight S and any point A?
3 - And how to find the symmetric of A in relation to S?
O.K. now translate the original three questions above.

#### Dr.Peterson

##### Elite Member
1 - How do you find a straight perpendicular to S and passes through point A?
2 - How to find the distance between any straight S and any point A?
3 - And how to find the symmetric of A in relation to S?
I take this to mean:

1 - How do you find a straight line perpendicular to a given line S that passes through a given point A?​
2 - How do you find the distance between a given straight line S and a given point A?​
3 - And how do you find the point symmetric to a point A with respect to a given line S?​

We still need something more: First, what topics are you studying, so we can know what methods are appropriate (e.g. vectors, coordinates and equations, Euclidean geometry, ...)?

Second, in what form are the line and point specified?

Finally, what have you tried, and what went wrong? If you showed any attempt, that would largely answer the first two questions. And if you think you have nothing to try, because you are asking for methods you have not learned yet, there really are things you could have tried. Or you could just show specific examples.

That's why we give you these instructions:

#### canvas

##### New member
$(1)\\S:\,\,y=a_1x+b_1\,\,\,\,\,\,\,A=(x_a,y_a)\\L:y=-\frac{1}{a_1}x+b_2\\A\in L\Rightarrow y_a=-\frac{1}{a_1}\cdot x_a+b_2 \Rightarrow b_2=y_a+\frac{x_a}{a_1}\\\red{y=-\frac{x}{a_1}+y_a+\frac{x_a}{a_1}}$CORRECTED

Last edited by a moderator:

#### canvas

##### New member
$(2)\\S:Ax+By+C=0,\,\,\,\,\,\,P=(x_0,y_0)\\\\d=\frac{|Ax_0+By_0+C|}{\sqrt{A^2+B^2}}$

#### canvas

##### New member
(3)

Just find the perpendicular line that passes through the point A=(x_1, y_1), then find the point of intersection of these two line - this point is the medium point and use the formula M=( (x_1+x_2)/2, (y_1+y_2)/2 ) where A'=(x_2, y_2)

#### JeffM

##### Elite Member
What in the world are straights in space?
5 cards in sequence when you are weightless.

#### Dr.Peterson

##### Elite Member
(3)

Just find the perpendicular line that passes through the point A=(x_1, y_1), then find the point of intersection of these two line - this point is the medium point and use the formula M=( (x_1+x_2)/2, (y_1+y_2)/2 ) where A'=(x_2, y_2)
All of your answers are for a two-dimensional context, not "in space". There's also at least one error -- can you find it?

I'm hoping vectors turn out to be appropriate, as they make the work at least easier to state, if not also to carry out.

#### Subhotosh Khan

##### Super Moderator
Staff member
5 cards in sequence when you are weightless.
I thought that was a "flush" in the toilet !

#### canvas

##### New member
All of your answers are for a two-dimensional context, not "in space". There's also at least one error -- can you find it?

I'm hoping vectors turn out to be appropriate, as they make the work at least easier to state, if not also to carry out.
R^2 is two-dimensional "SPACE".
I just didn't see the comment that he tells in R^3. There are no errors in these. Do not offensive dude, have a nice day.

#### canvas

##### New member
*Do not be that offensive*

#### Dr.Peterson

##### Elite Member
R^2 is two-dimensional "SPACE".
I just didn't see the comment that he tells in R^3. There are no errors in these. Do not offensive dude, have a nice day.

Don't be defensive, dude. Listening to correction is wise.

#### canvas

##### New member

Don't be defensive, dude. Listening to correction is wise.
Do you mean that I ate an 'x' in the final equation of L?

#### JeffM

##### Elite Member
R^2 is two-dimensional "SPACE".
I just didn't see the comment that he tells in R^3. There are no errors in these. Do not offensive dude, have a nice day.
It is obvious that the OP is not a native speaker. The very first response tried to elicit exactly what the OP meant by “space.” Your assumption that it was intended to mean a plane is very implausible, and your defense based on specialized mathematical usage is confusing rather than helpful to students, let alone students for whom English is not their native language.

Six of your twenty posts have been in this thread, and it is dubious whether a single one has been helpful.

EDIT: 7 out of 21.

#### canvas

##### New member
It is obvious that the OP is not a native speaker. The very first response tried to elicit exactly what the OP meant by “space.” Your assumption that it was intended to mean a plane is very implausible, and your defense based on specialized mathematical usage is confusing rather than helpful to students, let alone students for whom English is not their native language.

Six of your twenty posts have been in this thread, and it is dubious whether a single one has been helpful.

EDIT: 7 out of 21.
As you can see I'm not a native speaker too