New posts in euclidean-geometry

Find the distance $ID$ in the triangle below

geometry euclidean-geometry plane-geometry

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

Eritrea's Theorem

geometry euclidean-geometry triangles

What's the measure of the segment $BD$ in the figure below?

geometry euclidean-geometry plane-geometry

Difference between Euclidean space and $\mathbb R^3$

euclidean-geometry affine-geometry

The angle $168^\circ$ is constructible

abstract-algebra field-theory galois-theory contest-math euclidean-geometry

Does a set of $n+1$ points that affinely span $\mathbb{R}^n$ lie on a unique $(n-1)$-sphere?

geometry euclidean-geometry spheres

Can we prove this geometry question without too much calculation?

geometry euclidean-geometry

What novel results are there in Euclidean geometry in the last 50-100 years?

geometry euclidean-geometry math-history

Quadratic form(?) of Rotation [closed]

geometry euclidean-geometry

What is the minimum polynomial of $x = \sqrt{2}+\sqrt{3}+\sqrt{4}+\sqrt{6} = \cot (7.5^\circ)$?

algebraic-number-theory euclidean-geometry

Condition of existence of a triangle

geometry inequality euclidean-geometry analytic-geometry triangles

The number of the circles which are tangent to two circles and to a line

euclidean-geometry circles

Find $ \sin \left( \theta _{1}\right) ^{2}+ \sin \left( \theta _{2}\right) ^{2}+ \sin \left( \theta _{3}\right) ^{2}=? $

algebra-precalculus trigonometry euclidean-geometry systems-of-equations

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

geometry euclidean-geometry plane-geometry

Minimal Ellipse Circumscribing A Right Triangle

geometry euclidean-geometry analytic-geometry conic-sections plane-curves

Shadow time for a satellite on an inclined orbit

geometry euclidean-geometry dynamical-systems

If $AB\parallel DC$, $BC\parallel AD$, and $AC\parallel DQ$, find $\Bbb X$ in terms of the areas $\Bbb A$, $\Bbb B$, and $\Bbb C$.

geometry euclidean-geometry area plane-geometry polygons