# Questions tagged [geometry]

For questions about geometric shapes, congruences, similarities, transformations, as well as the properties of classes of figures, points, lines, and angles.

31,139 questions
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### Convex polyhedron with open faces

Convex polyhedron $P$ is a subset of $\mathbb{R}^n$ that satisfies system of linear inequalities \begin{align} a_{11}x_1 + \cdots + a_{1n}x_n & \sim_1\, c_1 \\ & \vdots \\ a_{p1}x_1 + \cdots + ...
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### how to find point lie on the arc [closed]

i have arc A ,i know startangle,endangle,startPoint,Endpoint,centre,radius of arc and i have point B, i like to find point B lies or not in arc A , i need formula or algorithum for this
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### What is the name of this lattice?

Suppose we have an atom at every point with integer coordinates in $\mathbb{R}^d$. Take a ($d-1$)-dimensional hyperplane going through $\mathbf{0}$ and orthogonal to $(1,1,1,\ldots)$. What is the name ...
166 views

### how do find the line lies on another line

I have Line $A$ with points $(1,1)$ and $(8,8)$ and another Line $B$ with points $(2,2)$ and $(4,4)$. I would like to prove Line $B$ lies on Line $A$. How can I do this?
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### How can I pack $45-45-90$ triangles inside an arbitrary shape ?
If I have an arbitrary shape, I would like to fill it only with $45-45-90$ triangles. The aim is to get a Tangram look, so it's related to this question. Starting with $45-45-90$ triangles would be ...