## draw circle through two given points in plot

Asked by Josefina Ottitsch

### Josefina Ottitsch (view profile)

on 3 Apr 2019
Latest activity Answered by the cyclist

### the cyclist (view profile)

on 3 Apr 2019
Hello
I have the following code
close all
x = -pi:0.01:pi;
a=sin(x)
plot(x,a)
hold all
plot(1,sin(1),'o')
plot(2,sin(2),'o')
I want my program to draw a circle between the two points, given in the program, using the least squares fitting method.
How do I draw a circle between two points (without knowing radius or middlepoint) ?
thank you so much!

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Answer by the cyclist

### the cyclist (view profile)

on 3 Apr 2019

In general, there are an infinite number of circles that pass through two given points.
If you don't care which one, then one possible algorithm is to
• for the center of the circle, find the midpoint of the line segment that connects the two points
• for the radius, use the distance from that midpoint to one of the points
It is easy to find formulas for these two steps.