Evan Chen
- Homography
A homography (or projective transformation) is a bijection of the projective plane that preserves collinearity and the cross ratio (hence mapping conics to conics).

Titu Andreescu and Gabriel Dospinescu
- Solving Elementary Inequalities Using Integrals
Why are integrals pertinent for solving inequalities? When we say integral, we say in fact area which is a measurable concept, a comparable one. That is why there are plenty of inequalities which can be solved with integrals, some of them with a completely elementary statement.

Frank M. White
- Integral Relations for a Control Volume
It is time now to really get serious about flow problems. The fluid statics applications of Chapter 2 were more like fun than work, at least in this writer's opinion. Statics problems basically require only the density of the fluid and knowledge of the position of the free surface, but most flow problems require the analysis of an arbitrary state of variable fluid motion defined by the geometry, the boundary conditions, and the laws of mechanics.