Interior #angles of a triangle sum to 180°

Mixing #stochastic process

Domain and range of a #function

Abu Rayhan al-Biruni (البيروني‎) calculated the Lunar eclipse , explains the different phases of the moon, estimate the radius and circumference of the Earth around 610 years before the Galileo Galilei. #history

#quotientgroup #sets #primenumbers

#eulersidentity #complex #pi

Indeterminate forms #lim

Prove that in a #parabola the tangent at one end of a focal chord is parallel to the normal at the other end.

φ(E[X])≤E[φ(X)]=E[Y] #jensensinequality

#history of maths

#sin #cos #angles

#hyperbolic moving paralel lines.
Non euclidean #geometry

Aristotle's wheel #paradox

Fast Fourier Transform #fft

#pi #circle

Cn is the number of monotonic lattice paths along the edges of a grid with n × n square cells, which do not pass above the diagonal. A monotonic path is one which starts in the lower left corner, finishes in the upper right corner, and consists entirely of edges pointing rightwards or upwards. Counting such paths is equivalent to counting Dyck words: X stands for "move right" and Y stands for "move up".