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# Intersection of two circles

## Intersection of two circles

(OP)
Hi,
I have two circles with centres (xo,yo) and (x1,y1) respectively. The two circles have radius R1 and R2. The circles are already plotted with help of a series of cumulative small angles (theta) and radius in excel. The two circles intersect at (xi,yi) and (xf,yf) which I have already found as well using mathematical equations.

I have a list of x,y co-ordinates of both the circles which is used to construct the circles. I want a list of x,y co-ordinates of both circles together ignoring the intersection portions between them, so that I can plot the perimeter portion of the circles (peanut shape in this).

Anderson

### RE: Intersection of two circles

Using the equations for the circles you can find the intersection points - there will be two intersections, so that would be four polar coordinates (two for each circle). Using these coordinates you can determine the angle between them relative to the radius of each circle. From this you can determine the arc length of each circle contained within the other circle. Take these two arc lengths from the combined circumferences; that will give you the value of the 'peanut-shaped' perimeter.

### RE: Intersection of two circles

(OP)
Thank you for the response.
I am actually a primitive user of excel and my apologies if it sounds too unprofessional.

With the use of scatter plot, the 2 circles with intersection has been drawn, but I do not want the chart to display the intersection arcs. Without manually removing the points in the arc, can the co-ordinates forming the perimeter "peanut shape" be listed and plotted in graph.

Thank you.

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