finding angle of slope...

[Brad]

Using Chart, Add Trendline, then selecting Linear in Excel to chart a linear
regression line on a series creates a new line on my chart with either a
positively or negatively sloped regression line.

Is there any way, using this built-in Excel feature, to convert the result
into degrees so that I can then label the regression line in degrees, for
example, 45 degrees?

My thanks for any ideas. Brad

 

[James Silverton]

Brad wrote on Wed, 21 Jun 2006 15:52:26 -0500:

B> Is there any way, using this built-in Excel feature, to
B> convert the result into degrees so that I can then label the
B> regression line in degrees, for example, 45 degrees?

You could display the equation of the trend line where the
coefficient of X is the slope tho' I believe it would be more
accurate, in earlier versions of Excel, to use LINEST to get the
slope; slope:=INDEX(LINEST(known_y's,known_x's),1). Then all you
have to do is convert the slope, which is the tangent of an
angle, to the angle = DEGREES(ATAN(SLOPE)). See LINEST and other
worksheet functions in HELP.


James Silverton.

 

[Bernard Liengme]

The functions SLOPE and INTERCEPT give the m and c of y=mx+c, respectively
Suppose A1 and B1 have text such as X and Y, while A2:A10 have the x-values
and B2:B10 have the y-values
In D2, I entered =SLOPE(B2:B10,A2:A10) and get a slope value (in my example
it was 2)
Now this slope is the tangent of the line; so ATAN(D2) will tell me the
angle
But like most computer programs,Excel thinks of angles in radians (the only
'pure' measure to use)
If I want degrees I need to convert the result to degrees; let's do it all
in one cell with formula =DEGREES(ATAN(D2))
Or it I want to be very clever I could use a single cell with
=DEGREES(ATAN(SLOPE(B2:B10,A2:A10)))
The answer displays as 75.96376
If I want to see degrees, minuets an second I will visit Chip's site at
http://www.cpearson.com/excel/latlong.htm and re-learn how to do it (I
actually like decimal values)
best wishes