MATLAB Answers

## Using (x-a) ^ 2 + (y-b) ^ 2 = r ^ 2, the values ​​of a, b and r are known. How do I find x and y values?

Asked by busra dogru

### busra dogru (view profile)

on 11 Apr 2019
Latest activity Commented on by Torsten

### Torsten (view profile)

on 15 Apr 2019
I know the values ​​a, b and r. (x-a) ^ 2 + (y-b) ^ 2 = r^2 providing the formula I want to calculate the x and y points . Thank you in advance for your help.

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## 1 Answer

Answer by Torsten

### Torsten (view profile)

on 11 Apr 2019

theta = linspace(0,2*pi,100);
x = a + r*cos(theta);
y = b + r*sin(theta);
plot(x,y)

busra dogru

### busra dogru (view profile)

on 11 Apr 2019
Now I understand better, thank you very much..
busra dogru

### busra dogru (view profile)

on 14 Apr 2019
Hello again. I can calculate x and y points with your code. I'm trying to check if these points are in the binary image. I get the following error when I run the following code;
[b, a] = find(newImage);
A = [a, b];
[m,n] = size(A);
B = 1;
t = 1;
while(t<51)
for p=1:m
while(B==1)
theta = linspace(0,2*pi);
x = A(p,1) + round(t*cos(theta));
y = A(p,2) + round(t*sin(theta));
x = x';
y = y';
if x == 0
x = 1;
end
if y == 0
y = 1;
end
B = A(x,y);
t = t+1;
end
end
end
disp(x,y);
Subscript indices must either be real positive integers or logicals.
Error in Untitled18 (line 79)
B = A(x,y);
What can I do to solve this error? Thanks in advance ..
Torsten

### Torsten (view profile)

on 15 Apr 2019
x and y are vectors of doubles of the same size as "theta" - so the setting B = A(x,y) doesn't make sense.

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