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0
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2answers
20 views

Surface whose points can all be connected by straight lines contained in the surface

I don't know the mathematical term used to define a surface whose points can all be connected by staright lines contained in the surface vs cannot all be connected by straight lines contained in the ...
2
votes
1answer
24 views

Is there a family of functions that includes triangle, sin, and square waves?

Is there a family of functions that includes triangle, sin, and square waves? ]2 If so, is there a way to parametrise them such that a single parameter sweeps from triangle through sin to square? ...
0
votes
0answers
18 views

Making a Net from a 2D Image

I'm trying to find the volume of the illustration Fig.1, I've taken a scale reference from the medium diameter of a strawberry and I’ve applied this scale to the remaining sides of the shape. Fig.1 is ...
0
votes
2answers
60 views

What are 3D objects called?

The first thing I did was Google this, nothing. I know that 0D objects are points, 1D objects, lines, 2d objects, Planes, but when we reach 3D representations of 2D planes, like a square to a cube, we ...
0
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0answers
18 views

What is the algorithm for the 3D rigid superimposition?

Someone here know how to perform a rigid superimposition in a 3D cartesian plane for two or more objects? Thanks for your time
0
votes
1answer
36 views

What is the name of this shape? (two arcs and two tangents)

Think the shape of a two-pulley belt or a fully tightened bicycle chain: If it was symmetrical, it could be called rounded rectangle, but not when the radii are not equal.
2
votes
1answer
37 views

name or formal description for the shape of a Pac-Man board

I'm looking for a name for the (finite, boundless, impossible) shape created by taking a square and wrapping it so that the opposite edges are coterminous (I think that's the correct usage, it's been ...
0
votes
0answers
84 views

Creating shapes, just with rotations

I have a game with orbiting objects, these objects can orbit around a point. But this point itself can orbit around a point. So my Question is, is it posible to create any closed shape with this ...
1
vote
1answer
68 views

5 geometric shapes all touching each other

I was playing aroud with shapes, which all connected. I managed to get 3 and 4 (http://i.imgur.com/MjOnY3e.png) shapes all connected to each other, but I can't get 5 to work in 2D. Does anyone have ...
1
vote
1answer
58 views

How many blocks are required to make the toy?

A pyramid shaped toy is made by tightly placing cubic blocks of $1\times 1\times 1 cm^3$.The base of the toy is a square $4\times 4cm^2$. The width of each step is $0.5cm $.how many blocks are ...
0
votes
1answer
18 views

Facets shared by two points on a convex polytope

I have a convex polytope of arbitrary dimension. Let $\mathcal{F} (A)$ denote the set of facets that vertex $A$ belongs to. If two vertices share an edge, is it true that the disunion of $\mathcal{F} ...
0
votes
2answers
191 views

The exterior angle of a regular polygon is $40$ degrees, how many sides does it have?

I have used the formulae $(n-2) \times 180^{\circ}$ and I have tried to work in algebra but I just can't do it
0
votes
0answers
58 views

Correct name of geometric shape

What is the correct name of an irregular pentagon that has 4 vertices in a square shape and one protruding perpendicular from the mid point of two of the vertices. As seen in this image:
0
votes
0answers
13 views

How to efficiently calculate points of intersection of a straight line and a contour?

Ex. I have an image, let's say 100x100 pixels with some shape on it. And a set of straight lines that are passing through origin located at some point of image, for example origin located at point ...
2
votes
0answers
23 views

How to restore 3d figure from two main cuts?

Imagine we have two perpendicular cuts of the 3d figure, that has vertical axis of symmetry as it shown on the picture: [ We know all the data from which these two cuts consists of(0X,0Y and 0Z data ...
-1
votes
2answers
54 views

Block Pyramids in Minecraft - total number of blocks

The total number of blocks within pyramids on Minecraft doesn't quite correspond with Square pyramidal numbers (on Wikipedia). Because of the blocky nature of the environment, the "even rows" of the ...
0
votes
0answers
99 views

What is this shape called?

I've encountered an unusual shape that I have no idea the name of. We have a sticker on the shape that tells us the equation $z^2 = \frac{x^2}{a^2-y^2}$ Here is a picture of the shape itself: ...
2
votes
0answers
54 views

Function to describe teardrop shape

If I fill a plastic ziploc-shaped bag with water, the cross section profile should be sort of teardrop shaped (assuming we ignore the edge effects of the bag being sealed on the sides as well as the ...
0
votes
0answers
17 views

Discretization of $W^{1,\infty} (\mathbb R^N, \mathbb R^N)$

I am working on a shape differentiation problem. I have a theoretical result that I want to implement numerically. Does anyone know of a reference for a discretization (finite sequence of subspaces ...
1
vote
1answer
86 views

Relationships between Schläfli symbol and geometrical properties of regular concave (star) polygons

In a Geometry class, we have been learning about the Schläfli symbol and how it is used to describe regular polygons with the notation {p, q}. I am studying a special class of concave polygons known ...
1
vote
0answers
61 views

Is there a name for a 2-dimensional dumbbell like shape?

Is there a mathematical name for a 2-dimensional shape in the general form of a dumbbell? That is two circular nodes connected by a center beam such as shown in this image from this answer. It could ...
0
votes
2answers
380 views

Given three sides of an isosceles trapezoid, find the smaller base side

I've been surprised at how challenging this problem is. Given an isosceles trapezoid, with the larger base b, the four angles, and the two equal sides c know, find the length of the shorter base a. Is ...
2
votes
1answer
81 views

Calculate angle on bent bar based on height

I'm writing a small piece of software that shows a preview of a bent rebar. I am however unable to figure out how to calculate the angle so the shape fits within given height $(B)$ requirements. $A, ...
0
votes
0answers
62 views

How to find the formula of a function from its graph?

I've got some data points (X/Y coordinates) that were apparently created using a certain formula that I want to reconstruct now. I've only got those points, and I can plot them (e.g. like in this). I ...
1
vote
1answer
208 views

How to solve this problem using spherical coordinates system?

The question is very simple: Volume inside the solid limited by:$ (X^2+Y^2+Z^2=16), (X^2+Y^2=4)$ using SPHERICAL coordinates system. The final answer however can be checked making a "cylindrical ...
0
votes
0answers
37 views

Fitting shapes of know sizes on another larger shape in diagonal fashion

How can I place shapes of known dimensions (with variation) on a larger shape, when intersection of these shapes is permitted and I must make the biggest gap between them? Please note that I wish to ...
2
votes
0answers
100 views

3D Shape with only coplanar faces?

I just thought of this problem, and it's bugging me that I can't find any sort of shape that fits it. Are there any 3D shapes with only faces that have coplanar matches with other faces in the shape? ...
0
votes
1answer
403 views

How you could you change the surface area formula for a cylinder to calculate the curved surface area of the half pipe?

Skateboarders use half pipes for doing tricks. A half-pipe is a half cylinder. Explain how you could manipulate the surface area formula for a cylinder to calculate the curved surface area of the ...
1
vote
0answers
72 views

What shapes fit evenly inside a Hexagon

So I'm designing a board game that uses a number of adjacent hexagonal boards. These boards need to be divided up into spaces (tiles) that players move through. I've been playing with using Hexagons ...
4
votes
2answers
169 views

Divide a square into different parts

This is a very interesting word problem that I came across in an old textbook of mine. So I know its got something to do with geometry, which perhaps yields the shortest, simplest proofs, but other ...
3
votes
1answer
125 views

How to find the center of a log spiral?

Given just a few points on a log spiral, how to find the center? Considering that the circle is a degenerate case of the log spiral, is there a way to generalize the method for finding circle centers ...
3
votes
1answer
55 views

Arrange 1-12 around a circle

This is a very interesting word problem that I came across in an old textbook of mine. So I know its got something to do with plain old algebra, which yields the shortest, simplest proofs, but other ...
4
votes
2answers
142 views

How to solve this riddle?

How to solve this riddle? All rooms have the same shape and size. Every room has one entrance, and two exits: one on the left, and one on the right (on opposite directions). Both exits lead to a ...
1
vote
0answers
57 views

A quadrilateral drawn in the complex plane, Show that ABCD is a square if and only if $i(a-c) = (b-d)$.

A quadrilateral drawn in the complex plane has vertices $A,B,C,D$, labelled anticlockwise. These vertices are represented, respectively, by the complex numbers a, b, c, and d. Show that ABCD is a ...
0
votes
0answers
35 views

Shape of generalized helix

This is a homework assignment that I fail to understand. The problem is to find the shape of a generalized helix $r=r(s)$ when the fixed vector is $v=(0,0,1)$ and $r(0)=0$. I have found forms that ...
0
votes
0answers
48 views

What do you call a torus with a center?

This may be a dumb question, but what is a torus with a center called? (Imagine a doughnut, without it's center taken out.)
-1
votes
2answers
88 views

Bisecting line segments in a tetrahedron. [closed]

Suppose that $OABC$ is a regular tetrahedron with base $ABC$. Suppose further that $T$ is the mid-edge of $AC$, $Q$ is the mid-edge of $OB$, $P$ is the mid-edge of $OA$, and $U$ is the mid-edge of ...
2
votes
2answers
129 views

Relationship between the side lengths of a tetrahedron and an inscribed tetrahedron with vertices at the centroids

Suppose that $OABC$ is a regular tetrahedron with sides having centroids $\lbrace E,F,G,H\rbrace$ also forming a regular tetrahedron. What is the relationship between the side lengths of $OABC$ and ...
2
votes
4answers
134 views

I call them squares. They called them arrays. What do they mean?

So I was in C++, and we had third graders come today to play our programs. Whilst the others just drilled them with problems, my game was subtract a square. It was fun watching them discover that ...
2
votes
0answers
127 views

whether any shape can be placed on a tiled surface?

After read "Prove that any shape 1 unit area can be placed on a tiled surface",I think on a surface of equal square tiles where each tile side is 1 unit long,the shape ,less than some constant C>1 ...
1
vote
2answers
54 views

Finding the missing length

How do i find the ST?? What more information do I need? I used Pythagorean theorem, but I still can't find the answer.
0
votes
1answer
21 views

Find correleation between values and degrees

I have an arc that starts at $252$ degrees and ends at $288$ degrees, I would like to assign non - linear values on it with this ratio: $1 - 180$ degrees. $5 - 135$ degrees. $10 - 90$ degrees. $30 - ...
4
votes
1answer
35 views

Find the “surface vertices” of a collection of points.

I am currently doing some experiments in order to simulate liquids. I have a collection of 3D points that interact with each other to form a body of water. I would like to form a mesh from these ...
0
votes
0answers
32 views

Possible areas within an integer grid

Given a 1x1 grid with 4 lattice points $[(0,0),(0,1),(1,0),(1,1)]$ (equivalent to a $2 \times 2$ grid of vertices), there are 2 shapes and areas that can be formed: a triangle and a square. There are ...
17
votes
8answers
2k views

Can someone explain 4th dimensional objects?

I'm not sure if I should ask this in mathematics or in physics. From what I can tell, there are only 3 dimensions: X, Y, and Z. However, I have seen a lot of things about fourth and even fifth ...
3
votes
1answer
72 views

Name for “3-dimensional figure-8” shape

Take a sphere or ellipsoid or similar (hereafter just called sphere) ... and imagine pinching it in the middle, deforming it by moving two points that were on opposite sides of the sphere inward until ...
18
votes
5answers
2k views

How to prove that it is possible to make rhombuses with any number of interior points?

I was given some square dot paper which can be found on this link: http://lrt.ednet.ns.ca/PD/BLM/pdf_files/dot_paper/sq_dot_1cm.pdf and was told to draw a few rhombuses with the vertices on the dots ...
2
votes
1answer
51 views

A “house” (pentagon) with square height $x$ and triangle height $\frac12x$…

Imagine a simple drawing of a "house," a triangle with half of the height of a square that it's laying on, to form a pentagon. If the square's height is $x$ and the triangle's height is $\frac12x$ ...
0
votes
1answer
46 views

Definition of the golden rectangle? [duplicate]

Is this true: The golden rectangle is defined as: X=A+B Y=A Y:X is as B:Y For bonus points: what other shapes with defined orientation but undefined size can be defined in an XY grid by using ...
0
votes
0answers
64 views

Does this construction method produce all possible convex pentagons (up to similarity)?

I read a question somewhere here about convex pentagons. I began to wonder if there was a way to list all possible convex pentagons and came up with the following method: 1) Draw a base line AB of ...