Category: General

Circle inscribed in a semicircle

There is black semicircle, which radius is $ R $. The red circle is tangentially inward to the semicircle and to the diameter in its center. The yellow on...

Automorphism group of Fano Plane

In finite geometry, the Fano plane is the finite projective plane with the smallest possible number of points and lines: 7 each. Why its automorphism grou...

Equality and its axioms

I'm reading a Wikipedia article about equality and its axioms and I'm wondering how we can prove (using equality axioms) that: If $x = y$ then $...

Limits notation

I'm wondering what is the difference in the use of $$\lim\limits_{x \downarrow a}$$ $$\lim\limits_{x \searrow a}$$ $$\lim\limits_{x \nearrow a}$$ $$\...