# Questions tagged [geometry]

Questions on the application of Mathematica to geometric problems. You might also consider adding the [graphics] tag, if appropriate.

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### Finding 3d circle center

Num calcn for Tria Center Can someone please help in finding an analytic expression for the center of a circle through 3 given points by modifying ( Solve in place of NSolve ) a conventional numerical ...
• 2,806
74 views

### Get the correct branch form Solve

I am reproducing the derivation in this article (exploration of a family of circles centered on an ellipse). I only need the outer curve, the results obtained from Mathematica are more complicated ...
• 4,868
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### Strange behaviour in GeometricTransformation

I came across the following strange behaviour with the GeometricTransformation function. ...
• 3,524
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### How to find PlanarAngle[] across periodic boundaries?

Suppose we have a collection of points selected as being within a certain radius (0.1) of myCenterPoint: ...
• 1,303
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### Divide a geometric region by (many) lines

Given a shape (e.g., a rectangle, a circle, etc.), how to divide it by $n$ randomly chosen lines. It is trivial to plot those lines (see figure below), using code like ...
• 417
1 vote
78 views

### How to find the center of gravity of fibers in image

I am trying to find the centers of gravity of my particles in a SEM image. I binarized the image (img) and with the input and help of previous suggestions on that topic (Creating graph out of ...
• 11
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### Hemisphere volume plot

I am trying to show an animation of the hemisphere volume. I tried to start with some radius and rotate it, to get an area of a circle. Then, I will stack up the circle in z-axis to make a hemisphere. ...
• 85
140 views

### How to combine several surfaces into a solid and compute its volume?

plot1 is taken from the BSplineSurface document. I add two Disk ...
458 views

### How to quickly test if two regions intercept?

If I randomly generated two cylinders, how do I test if they intercept? For example: ...
• 123
159 views

### How to draw two tangentlines to the circle in the complex plane

From the origin(0,0) of the complex plane, draw two tangent lines to the circle (see plot (p1)). The absolute value of a complex number is a vector from origin to complex number in complex plane. <...
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101 views

### How can I get the volume enclosed by two orthogonal cylindrical surfaces?

With the following code, I can only get the results when the radius of the ball and the half apex angle of the cone are specific values. ...
• 1,365
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### How can I get the volume enclosed by two orthogonal cylindrical surfaces (Radius is a variable, not a specific value)?

I can get the volume enclosed by two orthogonal cylindrical surfaces when the radius of the bottom circle of the cylinder is a specific value (for example, r1=r2=2): ...
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### Is there an inverse function of LineScaledCoordinate?

I know a useful function LineScaledCoordinate through animate-point-going-around-a-triangle, so does it have an inverse function? ...
• 6,510
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### Make polygon rolling along a line smoothly

I'm making an animation of a polygon rolling along the X-axis, the labels should keep their orientation and float is not allowed. Now lack of transitional status, is there an simpler way to add a ...
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### Quarter circle surface opening outward

I have a Graphics3D issue, I have a cylinder within a cylinder. I want to generate a surface from a quarter circle, but the quarter circle should be "curving ...
• 316
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### Problem with RegionMember

I think there is potentially a bug in RegionMember function, particularly in the RegionMember[reg] form. Can you evaluate the ...
• 8,528
1k views

### Checking if two line segments intersect

What is the fastest way of checking whether two line segments of the form Line[{p1,p2}] intersect at a point? I don't need to know what the point of intersection is,...
• 4,138
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### Plot is fast, solve is slow - what optimizations can be made?

I'm trying to solve a 3D geometric problem in terms of 3 variables (rotational angles), and I think the end is finally in sight - quite literally, I can see on a 3D plot where my solution exists. ...
• 101
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### Color regions defined by many lines

Consider the following code: ...
• 912
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### Rotation/Viewing options for 3D plots

Preamble In this post from several years ago: , it has been suggested that a "Globe" method is available for RotationControl. ...
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352 views

### How to draw arrows of certain length from a point, at a certain angle?

What's the specification to draw arrows of a certain length (from a reference point), at a given angle? Say, I want to draw an arrow of length 1 at 0 degrees, and one of length 0.5 at 90 degrees, each ...
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