# Thread: excel (2000/2002)

1. ## excel (2000/2002)

Can anyone tell me if there is a function in excel, and if not what formula i could use to calculate the distance between two points on the circumference of a circle, if all i input is the circumference of that circle and how many points there are? Eg. If my circle is say 2 metres in circumference, and there are 8 points around the circle, i want to know the distance between each and every point. So between point 1 and 2, 1 and 3, 1 and 4 etc, then 2 and 1, 2 and 3, 2 and 4 etc.
Many thanks.

2. ## Re: excel (2000/2002)

You are going to have to be more specific if you want more details:

If all the points are equally spaced. The distance is just the proportion.
If you have 8 equally-spaced points and the circum is 2 m:
Pt1 to Pt2 = (2m) / 8 * (2-1) = 0.25 m
Pt1 to Pt3 = (2m) / 8 * (3-1) = 0.5 m
...
Pt1 to Pt7 = (2m) / 8 * (7-1) = 1.5 m
Pt1 to Pt8 = (2m) / 8 * (8-1) = 1.75 m
Pt1 to Pt1 = 2m

If they are NOT equally spaced, you need to know the ANGLE between the points (which you did not give). Or the coordinates of the points and the center to calculate the angle:

In general:

ArcLength = Circumference / 360 * (ArcAngle)

ArcAngle = angle of Pt1-center-Ptx

Steve

3. ## Re: excel (2000/2002)

Do you want to know the staight line distance, or the Arclength distance?

Steve has givern an asnwer for the Arclength.

to find the straight line distance, I think you would need to use the cosine rule, as in each case you are trying to find the length of a side of a triangle, and you know the length of two sides, (the radii) and the size of the included angle.

a squared = b squared + c squared - 2bcCosA

Sorry I don't know how to put in superscripts here.

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