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I have given the center point and the radius of a circle but i am interested in the most right point which is lying on that circle.

edited: thanks for the comments. I have the central point c and have the radius r as well. And my question was what is the equation to get the most right point p on the circle surrounding the center by the given radius.

r = sqrt((p1-c1)(p1-c1) + (p2-c2)(p2-c2))

then i am looking for the (p1,p2) point

At the end I found it out with the help and hint from you. As I mentioned I had the central point C and the radius R and I was looking for the most right point P on the edge of the circle. My approach what finally helped was to calculate a square around the circle (bounding box) and take as x coordinate for the P point the x coordinate of the top right corner of that bounding box, and the y coordinate for the P point the y of the C point. Thanks for every help, as far as it showed me the right direction.

P(x,y)=(xC,yC)+v⃗ R <--- this helped also as the v⃗ R is a normal vector on the right edge of the mentioned bounding box.

Csabi
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  • I assume you have the equation. Set $y$ equal to the height of the center and solve for $x$. If that's not what you want, [edit] the question to tell us what you do know. – Ethan Bolker Dec 03 '18 at 11:19
  • It's a very vague question but still i suggest you use parametric coordinates for this purpose – 28ADY0901 Dec 03 '18 at 11:19
  • If i understand it right:Center $\vec{c}$, radius $r$, $\vec{p}$ the point you are looking for. $\vec{p} = \vec{c} + r \vec{e_x}$, where $\vec{e_x}$ is the unit-vector in x-direction. – denklo Dec 03 '18 at 11:20
  • thanks for the comments. I have the central point and have the radius as well. And my question was what is the equation to get the most right point on the circle surrounding the center by the given radius – Csabi Dec 03 '18 at 11:26
  • It seems from the equation that you don't have the radius. If you have the center and radius, please include these in your post, so we'll be better able to help you. – Cameron Buie Dec 03 '18 at 11:44
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    @Csabi It woulb be useful if you could show your work here editing your question. – user Dec 03 '18 at 21:16

2 Answers2

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HINT

Assuming the center at $C(x_C,y_C)$ any other point on the circle with radius $R$ can by obtained by

$$P(x,y)=(x_C,y_C)+\vec v_R$$

with $|\vec v_R|=R$.

user
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  • Hi thanks for the answer, but i would like to know if it is possible to have the most right point received by an equasion – Csabi Dec 03 '18 at 11:29
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    @Csabi You need to figure out what the vector $\vec v_R$ needs to be. You have already received some big hint by the comments. – user Dec 03 '18 at 11:31
  • thanks your answer showed me the right way. I have edited my answer and showcased my solution. @gimusi – Csabi Dec 05 '18 at 06:55
  • That's nice! Well done, Bye – user Dec 05 '18 at 07:48
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I would draw a picture. How is the $x$-coordinate of the rightmost point related to the $x$-coordinate of the center? How are their $y$-coordinates related?

Cameron Buie
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