# Category Archives: General

## Uniqueness of hyperbolic geodesics

The Poincare’ model of hyperbolic geometry consists of the unit disk where the geodesics are arcs of circles perpendicular to the unit circle . It turns out that given two points there is a unique circle orthogonal to passing through … Continue reading

## Modulus of Path Families on Graphs

These notes approximately follow a presentation Mario Bonk gave at the Workshop on Discrete and Complex Analysis, Montana State University, July 19-23, 2010. We follow the paper of Haïssinsky “Empilements de cercles et modules combinatoires”. Ann. Inst. Fourier (Grenoble) 59 … Continue reading

## An elementary introduction to data and statistics

The first part of this material should be accessible to a fourth-grader, the latter part to a middle-schooler. The initial Mental Math trick can be taught without algebra, even though in order to describe the method on paper we found … Continue reading

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## Complex Numbers

A complex number can be written in Cartesian coordinates as , where is the real part and is the imaginary part. Or it can be written in polar coordinates as , where is the absolute value and is the point … Continue reading

## An Elementary Introduction to Data and Statistics

Elementary Introduction to Data and Statistics