Newbetuts

For regular tetrahedron $ABCD$ with center $O$, and $\overrightarrow{NO}=-3\overrightarrow{MO}$, is $NA+NB+NC+ND\geq MA+MB+MC+MD$?

geometry contest-math euclidean-geometry geometric-inequalities geometric-transformation

What's the measure of the segment $PD$ in the triangle below?

geometry euclidean-geometry plane-geometry

Does the nine point circle generalise to some theorem about n-spheres and n-simplices?

geometry euclidean-geometry

Unique characterization of convex polygons

geometry computational-geometry

Triangle problem

geometry

Proofs: the running in the sun conjecture (I made it up - explained below). Is it true and how can it be proven?

geometry multivariable-calculus

Prove there are at least $2$ lines with the property that each of them divides the plane into $2$ regions with the same number of red and blue points. [duplicate]

combinatorics geometry puzzle

How to prove the parametric equation of an ellipse?

geometry conic-sections parametric

Drawing a tetrahedron from a parellelepiped to convince myself it is 1/6th the volume,

linear-algebra geometry determinant volume

Finding all $f:\mathbb R^3\to\mathbb R^*$ satisfying $f(O)=f(A)f(B)f(C)f(D)$ for any non-degenerate tetrahedron $ABCD$ with incenter $O$

geometry contest-math 3d

Cylinder-ray intersections equation

geometry mathematical-physics computational-mathematics

Why are Banach manifolds not so popular?

geometry soft-question manifolds

Proving that $\sum \overline{PV_i}^2=\frac{nl^2}{4}\left(1+2\cot^2 \frac{\pi}{n}\right)$

geometry

Eritrea's Theorem

geometry euclidean-geometry triangles

Intersection of hypercube and hyperplane - features of resulting polytope?

geometry polytopes

New posts in geometry

find the maximum possible area of $\triangle{ABC}$

How to "coordinate bash" a geometry problem?

Line integral of a force field

What shape is the locus of a 3D corner with a circular ring that touches the sides of the corner?

Proof that $n$ planes cut a solid torus into a maximum of $\frac16(n^3+3n^2+8n)$ pieces

For regular tetrahedron $ABCD$ with center $O$, and $\overrightarrow{NO}=-3\overrightarrow{MO}$, is $NA+NB+NC+ND\geq MA+MB+MC+MD$?

What's the measure of the segment $PD$ in the triangle below?

Does the nine point circle generalise to some theorem about n-spheres and n-simplices?

Unique characterization of convex polygons

Triangle problem

Proofs: the running in the sun conjecture (I made it up - explained below). Is it true and how can it be proven?

Prove there are at least $2$ lines with the property that each of them divides the plane into $2$ regions with the same number of red and blue points. [duplicate]

How to prove the parametric equation of an ellipse?

Drawing a tetrahedron from a parellelepiped to convince myself it is 1/6th the volume,

Finding all $f:\mathbb R^3\to\mathbb R^*$ satisfying $f(O)=f(A)f(B)f(C)f(D)$ for any non-degenerate tetrahedron $ABCD$ with incenter $O$

Cylinder-ray intersections equation

Why are Banach manifolds not so popular?

Proving that $\sum \overline{PV_i}^2=\frac{nl^2}{4}\left(1+2\cot^2 \frac{\pi}{n}\right)$

Eritrea's Theorem

Intersection of hypercube and hyperplane - features of resulting polytope?