Sum of points on the line

May 2010
13
0
Hi,
I have lines such as that first line has 2 point (1,0,-1) and (4,1,-3) and when i check the sum which is (5,1,-4) it is not on the line.
Then I have line that has (2,-1,3) and (10,-5,15) and its sum is (12,-5,15) is on the line. I was wondering why the sum in some cases is on the line and in some it is not.
 

skeeter

MHF Helper
Jun 2008
16,216
6,764
North Texas
Hi,
I have lines such as that first line has 2 point (1,0,-1) and (4,1,-3) and when i check the sum which is (5,1,-4) it is not on the line.
Then I have line that has (2,-1,3) and (10,-5,15) and its sum is (12,-5,15) is on the line. I was wondering why the sum in some cases is on the line and in some it is not.
it works because one of the points is a scalar multiple of the other ...

5(2,-1,3) = (10,-5,15)
 
May 2010
13
0
yes but.....

Yes exactly. We are talking here about the point not vector scalars. those are just point not vectors. I didnt know we can take scalar of points....My assumption is that if we have vector for example (1,2,3) then any vector k(1,2,3) is on same line...
am i correct?
 

skeeter

MHF Helper
Jun 2008
16,216
6,764
North Texas
Yes exactly. We are talking here about the point not vector scalars. those are just point not vectors. I didnt know we can take scalar of points....My assumption is that if we have vector for example (1,2,3) then any vector k(1,2,3) is on same line...
am i correct?
yes
 
May 2010
13
0
but....?

but those values are point not vectors.
 

skeeter

MHF Helper
Jun 2008
16,216
6,764
North Texas
but those values are point not vectors.
but they behave the same way as vectors ... draw a line from the origin to the point.