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**tommmy****Guest**

hi,

I have a line drawn on a grid all i know is start and end co-ords of the line from the start co-ord i need to calculate a point on the line that is just slightly further down the line than the first point. is this possibe?

**Patrick****Real Member**- Registered: 2006-02-24
- Posts: 1,005

You should be able to find the slope, and the y intercept of the line. When you have that, please reply again, and I'll (we'll) help you out, if it's still needed.

*Last edited by Patrick (2006-04-24 01:09:27)*

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,684

We also have a page that can calculate the equation automatically here: Straight Line Graph Calculator, but it is better to understand by reading the pages that Patrick mentioned.

Once you have the equation you can calculate any point on the line you want.

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**tommmy****Guest**

thanks for your help guys

i would caclulate the gradient and the y intercept but it is for an arbitary line.

from the material given i can understand how the maths works how ever i dont see how i can find a point a little down the line unless i know either an x or a y that is on the line near to where i want the new point to be ( if u can understand what i mean, i know it isnt that clear)

**Patrick****Real Member**- Registered: 2006-02-24
- Posts: 1,005

Okay, let the next step be this:

Write the co-ords here on the board, and we'll see what we can do to help you

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**tommy****Guest**

Patrick wrote:

Okay, let the next step be this:

Write the co-ords here on the board, and we'll see what we can do to help you

that was my point with the last post it isnt for a set line it is for an arbitary line.

**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,684

I think Patrick just wanted an example to work off.

So, lets use (2,3), (7,8)

The equation is y = x+1

So, what is "down" ? If you mean lower "x", then just pick an x-value slightly less than the smallest of the two x-values.

The x-values are 2 and 7, the smallest is 2, and "slightly less" would be 1.9

y = x+1 = 1.9+1 = 2.9

So "slightly down" would be (1.9,2.9)

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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