New posts in triangles

What is the name of this theorem of Jakob Steiner's, and why is it true?

geometry euclidean-geometry triangles

Do two right triangles with the same length hypotenuse have the same area?

geometry triangles area

How to calculate the area of a 3D triangle?

triangles 3d area

Maximum value of $\sin A+\sin B+\sin C$?

geometry trigonometry inequality optimization triangles

Length of the side of a similar triangle

geometry triangles area

Show that the area of a triangle is given by this determinant

linear-algebra determinant triangles area

Find the area of ​the triangle EGB.

geometry euclidean-geometry triangles area plane-geometry

Are there any other "involutive" (a la the orthocenter) points on the Euler line?

geometry euclidean-geometry triangles

Find the area of ​the shaded region: in the figure

geometry euclidean-geometry triangles area plane-geometry

Finding out the area of a triangle if the coordinates of the three vertices are given

geometry triangles coordinate-systems area

What's a proof that the angles of a triangle add up to 180°?

geometry triangles

What is the most elegant proof of the Pythagorean theorem? [closed]

geometry algebra-precalculus euclidean-geometry triangles big-list

$\tan A + \tan B + \tan C = \tan A\tan B\tan C\,$ in a triangle

algebra-precalculus trigonometry triangles

What is the probability that a point chosen randomly from inside an equilateral triangle is closer to the center than to any of the edges?

calculus probability geometry triangles geometric-probability

Is the blue area greater than the red area?

geometry inequality triangles area

Finding an angle within an 80-80-20 isosceles triangle

geometry triangles

Law of sines on SAS triangles?

triangles

V.I. Arnold says Russian students can't solve this problem, but American students can -- why?

geometry triangles area puzzle word-problem