# Tagged Questions

2answers
244 views

### Need a little help understanding this triangle concept. - Thales Theorem

The question is: ...
2answers
58 views

### A question on Trigonometry (bisector)

If two bisector of a triangular is equal, then it is Isosceles triangular.
2answers
54 views

### Calculating meeting point where line intersects arch

How do I find the point $p$ where the arch meets the red line if the angle of the blue are is known and the height of the yellow?
1answer
152 views

### Algebra question about Triangle Interiors

I was reading about Triangle Interiors on Wolfram Alpha: http://mathworld.wolfram.com/TriangleInterior.html and they have a simple equation: \mathbf{v} = \mathbf{v}_0 + a\mathbf{v}_1 + ...
1answer
50 views

### Does the orthocenter have any special properties?

Each of the commonly known triangle centers I know has some sort of special property. For example: The incenter is the center of the inscribed circle. The circumcenter is the center of the circle ...
1answer
90 views

### Altitude of tetrahedron?

I'm really curious to know any relationships between the altitude of a tetrahedron and how the foot of this altitude splits the base triangle. For example if you have a tetrahedron PABC with apex P, ...
1answer
33 views

### P is a point in triangle $ABC$, what is $[APC]$?

Moderator Note: This question is part of an ongoing contest on Brilliant.org, and will be unlocked in 1 week. P is a point in triangle $ABC$. The lines $AP$,$BP$, and $CP$ intersect the sides ...
1answer
122 views

### Geometry - optimal 2D mesh between X expendable points

Say you have X points on a plane. If you connect two points, you form a line. Connecting three points forms a triangle. A line cannot cross a line, and a smaller triangle cannot be created inside a ...
1answer
72 views

### Prove $(b-c)\sin A+(c-a)\sin B+(a-b)\sin C=0$

Prove the following equation, when you consider it as $BC=a$, $CA=b$, and $AB=c$ in a triangle　$ABC$. $(b-c)\sin A+(c-a)\sin B+(a-b)\sin C=0$
1answer
51 views

### Gergonne Point of a triangle coinciding with other triangle centers

I am trying to prove the following: Let $T$ be the Gergonne point (the intersection of the lines that connect the points of tangency of the incircle with the vertices of the triangle) of \$\triangle ...
1answer
38 views

### Triangle $z$-index interpolation between the vertices

I got a $2$D triangle, each vertex has a $2$D coordinate with a $z$-index value (NOT a $z$ coordinate!). The $z$-index value indicates whether a vertex lays on, in front of, or behind your screen ...
1answer
152 views

### Squares in a triangle?

I've got some trouble... IJKL is a square and B, I, J, C are aligned (alternatively, |IJ| is confounded with |BC|. h is the height of acute $\triangle$ ABC from A to side BC. C1 is the red ...
1answer
113 views

### Barycentric coordinates of a triangle

I have to do what described in the picture below. Any ideas on how to do this?
1answer
58 views

### how to find(measure,calculate) the distance (height,length) of an object?

I am trying to develope code ,so i need a mathematics help to proceed,please help me to find distance of an object using trigonometry r any applicable maths without using any sensors r external ...
0answers
73 views

### triangles in a grid of $n\times n$ with positive coordinates

I need to count the number of triangles formed in a grid of $n\times n$ with positive integer coordinates $(0..n)$. For example for $n = 1$ the answer is 4.
0answers
253 views

### Euler's Line of a medial triangle

I have the following problem with a comment below on the steps that I took so far. Here is the example: Let triangle ABC be any triangle. The midpoints of the sides in Triangle ABC are labeled \$A', ...
0answers
157 views

### Does “triangle” in English exclude degenerate triangles?

Just for fun read few problems on the projeteuler.net website. Number 276 found interesting: Consider the triangles with integer sides a, b and c with a ≤ b ≤ c. An integer sided triangle ...
0answers
32 views

### Proving that the circumcenter is the centroid

Given a triangle and its centroid, we know that the 3 line segments between the centroid and each of the vertices of the triangle divide the triangle into three smaller triangles. Prove that the ...
0answers
21 views

### maximum length of a scaled vector in a triangle (simplex)

Given a triangle (or, in general, a simplex) $T$ and a vector $\vec{s}$, I'd like to compute the quantity $$\max\{|x-y|: x,y\in T, x-y = \alpha \vec{s}, \alpha\in\mathbb{R}\}$$ i.e., the maximum ...
0answers
114 views

### Finding side and angle of isosceles triangle inside two circles

I'm having a problem that I'm not sure how to solve (or if it's even possible). It's not homework, just something i'm struggling with for a project. :) Basically, there are two circles, represented ...
0answers
31 views

### Two coloured plane

Can you prove that For any two angles $θ,ϕ$ there exists a monochromatic triangle that has angles $θ,ϕ,180−(θ+ϕ)$ in two coloured plane?
0answers
58 views

### How to find the inverse position inside a triangle

If i were standing in a triangle - How do i calculate the inverse of my position? Can it be done? It's easy inside a rectangle, but I can't think of how you would do it inside of a triangle. I'm ...
0answers
34 views

### Triangular exponentation logarithm and inverse

The generalized formula of triangular exponentation on real numbers field is $x ^ {\triangle y} = \frac {1} {y \cdot B (x, y)} = \frac {\Gamma(x + y)} {\Gamma(x) \cdot \Gamma(y + 1)}$ It's my ...
0answers
326 views

### General formula for computing triangular gaussian quadrature.

While this is a simple question, I'm totally lost. Is there any general formula for generation of n-point gaussian quadrature over a triangle? I'll use this formula to generate a variable-point (7, ...
0answers
37 views

### Law sines in Spherical Triangle $\rightarrow$ Law sines in plane triangle

Could any one tell me how to estimate or get law of sines in Spherical Triangle to The Law of Sines in Plane Triangle? i.e $\frac{\sin a}{\sin A}=\frac{sin b}{\sin B}=\frac{\sin c}{\sin C}$ to ...
0answers
55 views

### Finding a formula for perimeter of triangles in triangle

I hope you are familiar with counting triangles in triangle problem. I've studied it a little recently. Now i want to find a formula for sum of perimeters of this all triangles but i don't know how to ...
0answers
55 views

### Sum of angles in a hyperbolic triangle with one ideal angle

I want to calculate the sum of the angles of the triangle formed in the hyperbolic plane from the points $(-1,1), (0,1)$, and $(1,1)$. This forms an angle at the origin which has an infinite slope for ...
0answers
54 views

### Figuring out angles of a second triangle based off of one side of a first

My friend and I are developing some image tracking software for a robot we are creating and we have this right here: ...
0answers
80 views

### Unknown depth issue: Triangle, Pyramid, Rotation, Translation, Zoom?

Edit: Had to delete the 2nd picture Another tricky question. What you can see here is my physical pyramid built with 3 leds which form a triangle in 1 plane and another led in the mid center, about ...
0answers
63 views

### Determining a point in 3D space

So given a point, a rotation around the y-axis, a rotation around the x-axis, and a distance, how can one calculate the relative point in space? For example, the beginning coordinates are (0,0,0). ...
0answers
31 views

### Looking for different (analytical) approaches to a problem

Given 5 points in the plane any three of which are vertices of a triangle. Prove that among these triangles there is an obtuse triangle. I was able to prove it by examining all possible cases. I ...
0answers
33 views

### Rotate a triangle to next 'visible' side

I have a triangle along the y/z axis (I can only see the flat side facing me). How do I rotate it around the x axis so that the next side faces me?
0answers
130 views

### pixels in a projection of a triangle in 3d space onto a 3d plane through a pinhole camera

I have a triangle in 3d space. The x and y components of its vertices make a 2d right isoceles triangle. I am projecting it through a pinhole onto a plane. The projected triangles on the plane are now ...
0answers
75 views

### Get value of angle with 45 degrees as maximum and 0 and 90 degrees as minimum

I want the calculate the "value" of an angle in such a way that: The angle of 45 degrees corresponds with the maximum value of 1 The angles of 0 and 90 degrees correspond with the minimum value of 0 ...
0answers
129 views

### Uniform Random Points on a triangle using only edge plane normals

For a triangle $ABC$ in 3D (each point has x, y, z coordinates) is it possible to generate uniform random points on the triangle from only the following data: Normal of the triangle plane \$N = ...
0answers
161 views

### How to find the last coordinate of an isosceles triangle

I'm having some trouble trying to find out how to find the final coordinate on an isosceles triangle. Here's a list of information that I have: The length of the two equal sides (A and B) The angle ...
0answers
177 views

### problem finding a 2D Point in a triangle

I have a Triangle with 3 Points - A, B and C and the angle alpha A and B are fixed. C is any point at the side of 'b' Alpha has at A and B the same size I need to find any Point on side 'a' except B ...
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