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**sammy182****Member**- Registered: 2006-09-26
- Posts: 1

when we find slope of a line, why is the change in y in the numerator and the change in x in the denominator?

An answer as soon as possible will be greatly appreciated!

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**John E. Franklin****Member**- Registered: 2005-08-29
- Posts: 3,588

Well say you wanted Run over Rise instead, then the Run is the X in the top and OVER the Rise, the Y. But this is the reciprocal of what you asked for.

Your rise over run is 0 for a flat line, and infinity or maybe undefined for a vertical line.

A 45 degree angle is one over one, or 1/1, a slope of 1.

We could get more philosophical about this, perhaps someone else will dig deeper?

**igloo** **myrtilles** **fourmis**

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**Prakash Panneer****Member**- Registered: 2006-06-01
- Posts: 110

Hi sammy182,

The slope of a line measures the steepness of the line.

Most of you are probably familiar with associating slope with "rise over run".

Rise means how many units you move up or down from point to point. On the graph that would be a change in the y values.

Run means how far left or right you move from point to point. On the graph, that would mean a change of x values.

In another way,

The slope m = tan x.

Here, x is nothing but angle made by the horizontal line (x axis) with the slant line.

tanx is nothing but opposite side/adjescent side.

Opposite side is nothing but y axis.

That is, change in y coordinate.

Adjescent side is nothing but x axis.

That is, change in x coordinate.

Hope you will understand the concept.

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