MATLAB: Calculate an angle and distance from three points

angledistancethree points

hi…How to calculate an angle and distance from three points? ex P1 = (x=2, y=50) P2 = (x=9, y=40) P3 = (x=5, y=20)

Best Answer

I'll show you how to find one of the angles in the triangle P1 = [x1;y1], P2 = [x2;y2], P3 = [x3;y3]. The inner angle at vertex P1 is given by:

 A1 = atan2(abs((x2-x1)*(y3-y1)-(x3-x1)*(y2-y1)), ...
                (x2-x1)*(x3-x1)+(y2-y1)*(y3-y1));

As for the "distance", please tell us what kind of distance you have in mind. Distance from what to what?

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MATLAB: How can i find angle with x-axis of a plot in matlab

p1 = 0.00053537
p2 = -8.1393e-018
p3 = -0.00044699
x=0:0.1:10
y = p1*x.^2 + p2*x + p3
angles=angle(x+j*y)

MATLAB: How to traverse a circle while identifying given points

Let P1 = (x1,y1), P2 = (x2,y2), P3 = (x3,y3) be the three points and their respective coordinates. Perform these computations:

   A4 = 2*((x2-x1)*(y3-y1)-(x3-x1)*(y2-y1)); % Four times triangle's signed area
   R2 = [x1^2+y1^2,x2^2+y2^2,x3^2+y3^2]/A4;
   x0 = dot([y2-y3,y3-y1,y1-y2],R2); % Coordinates of circle's center
   y0 = dot([x3-x2,x1-x3,x2-x1],R2);
   a1 = mod(atan2(-(x1-x0),y1-y0),2*pi); % Angles counterclockwise
   a2 = mod(atan2(-(x2-x0),y2-y0),2*pi); % from "top"
   a3 = mod(atan2(-(x3-x0),y3-y0),2*pi);
   [~,ix] = sort([a1,a2,a3]);
   M = [x1,y1;x2,y2;x3,y3];
   M = M(ix,:); % Points in order counterclockwise from top

Array M will be the coordinate pairs listed in counterclockwise order around from the "top" of the circle. If you want to go in clockwise order, just apply 'fliplr' to 'ix' or else do a descending 'sort'.

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MATLAB: How can i find angle with x-axis of a plot in matlab

MATLAB: How to traverse a circle while identifying given points

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