How to prove whether it may be a parallelogram.
127185
How to test whether a set of four points can form a parallelogram
49087
Show that a norm on an inner product space satisfies parallelogram law.
36628
How do I prove this method of determining the sign for acute or obtuse angle bisector in the angle bisector formula works?
109880
Prove that the perpendiculars from P,Q,R to BC,CA,AB respectively are also concurrent.
121469
Proof of observations on natural numbers being expressed as differences of squares.
97515
Is this graph a planar graph or not?
79452
How to prove that it is a group?
63952
Disproving: If $(\Gamma\vdash(\phi\,\lor\psi))$, either $(\Gamma\vdash\phi)$ or $(\Gamma\vdash\psi)$ is true
39416
The space obtained by identifying the antipodal points of a circle
32509
Proving a statistic is ancillary
100399
A doubt with a part of a certain proof.
70021
Verify if symmetric matrices form a subspace
80229
How to prove this curiosity that has to do with cubes of certain numbers?
83449
Proof with 3D vectors
88294
Determine which circuits are parallel and which are in series
121106
Parallelogram law valid in banach spaces?
124373
Area of a parallelogram, vertices $(-1,-1), (4,1), (5,3), (10,5)$.