Need help finding the points positions [closed] - math

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Here you can see a representation of the problem I need to solve
http://imageshack.us/photo/my-images/542/002yw.png http://imageshack.us/photo/my-images/542/002yw.png
I've two circles defined by their positions BS1 and BS2.
Now I need to get the position of the point A and the only data I've is the distance from point BS1 that is defined by its radius.
Can someone please tell me how can I find the coordiinates of point A?
Thank you very much
PD: I need to do the same with point B.

For simplicity lets say, on your left side of the image you have a center c1, radius r1, and point A. On the right side center c2, radius r2 and point B..
A = ((s1-s2)/|s1-s2|)*r1 + s1
B = ((s2-s1)/|s1-s2|)*r2 + s2
Do not forget, this are vectors.. If you can not understand this equation, tell me and Ill explain it to you.

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Finding focal length from image size and FOV [closed]

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I have bumped into the following statement in an Engineering journal. The statement is mentioned on right side example.
A 640x480 image with a horizontal FOV of 47 degrees gives focal length
f = 740 pixels.
Please let me know the calculations behind this as I am very new to Computer vision.
AFAIU 740 is not the exact answer for such data but close enough. According to my understanding
f = (width/2) * ctg(HFOV/2)
which give me f = 735.95. And to reverse for f = 740 the HFOV should be 46.77°.
The math behind is following: assume that on their Figure 2 Y1 is actually the top point on the sensor (I'll use vertical field of view here instead of horizontal because it allows me to use that image). Now consider the triangle O-P-Y1. In that triangle ∠P is half of the FOV. On the other hand ctg(∠P) = ctg(FOV/2) is OP/OY1 which is f/(height/2).

Some math abaut circle need mathematical formula [closed]

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I have no much time to research net, so can somebody derive the formula for calculating the point belonging to the circle?
as u can see we have point 5,-5 and center, and radius and angle. Thanks for advance, i know that isnt programming problem, but I need this to my project. OFC I see thats point 1,-1. but my pc probably will not ;/
For points inside the circle with radius R and center X,Y:
point (x,y) is inside the circle if:
(X-x)^2+(Y-y)^2 < R^2
Is that what you're after? No.
So what you need is a translate - rotate - translate.
So X,Y is the centre, x,y is the point and angle is the angle in degrees
# Translate
x = x-X ; y = y-Y
# Rotate
rad = angle*M_PI/180
xr = x*cos(rad) + y*sin(rad)
yr = -x*sin(rad) + y*cos(rad)
x = xr+X ; y = yr +Y
So if you only want 90 degrees, replace cos(rad) with 0 and sin(rad) with 1.

Determining Vector points on a circle [closed]

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This question does not appear to be about programming within the scope defined in the help center.
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I have a problem it is like trig and pre calc. We are given vector points for OA which is (6 0) and vector OB (-6 0) and OC (5 root11) and they are all points on a circle with a radius of 6. How exactly do you determine or show that these points lie on the circle?
For any three points which are not mutually co-linear, there is a point equidistant from each member of the set. Finding this point given three arbitrary points (and not given the radius) is a much more informative project if you're learning trigonometry.
In your example, the solution is simple: x2 + y2 = r2. Each of the points you provided have values such that the sum of their squares equals 36, as expected for a circle of radius 6. Your problem is especially easy because the circle in question is already centered on the origin.

Calculate destination point [closed]

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I want to draw a 3d line from one 3d point to another 3d point.
I know the source point, but need to calculate the destination point. I have the angle and the length of the line. The y coordinate (the height) is the same for the source and the destination point.
Thanks
Basic trig, imagine a bunch of triangles along the various planes and solve for the sides/angles you want to know.
If you give us some sample values for what you already know we can show you the maths.

move a small circle around a big circle [closed]

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this i an interview question i encountered with HULU.
Given two circles, one has radius 1 and the other has radius 2. Let the small one rotate along the perimeter of the big one. how many circles will the small one rotates when it has moves one round inside the big one? and what about outside?
The perimeter of the circle of radius 1 is 2*PI*1 and the other one is 2*PI*2.
Then when the little circles rotates inside it makes 2 round and same thing at the outside... Maybe I don't understand anything...
how many diameters of the small circle are in one diameter of the big one?

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