Pythagorean Theorem — Visual Proof in 10 Seconds

The Parametric Equation of an Ellipse

The Standard Equation of an Ellipse

Area of Ellipse — Formula Derivation (Proof)

A Stretched (or Shrunken) Circle is an Ellipse

Optical (Reflective) Property of an Ellipse

What is Ellipse? — How to Draw It, Focal Points, Definition

Pythagorean Theorem — Visual Proof in 10 Seconds

A New Website

Domain, Codomain and Notation of a Function

Introduction to Functions — People in Rooms Example

Equal Perimeters and Areas Problem — Circular Sector with Equal Perimeter and Area as Square

Area of Circular Sector (Circle Sector) — Formula Derivation (Proof), Example

Equal Perimeters and Areas Problem — Annulus (Circular Ring) with Equal Perimeter and Area as Square

Area of Annulus (Circular Ring) — Two Formulas, Perimeter, Width, Example

Area of Circle — Formula Derivation (Proof), Example

The Last Day of the Decade — December 31, 2020

Circumradius and Area of Triangle — Find Radius of Circumscribed Circle Using Area and Sides

Inradius and Area of Triangle — Find Radius of Inscribed Circle Using Area and Semiperimeter

The Sum of the First 100 Numbers — Method to Find It (The Sum of the First n Numbers)

Heron’s Formula — Find Area of a Triangle Using Lengths of Its Sides (Example, Formula Derivation)

Mutilated Chessboard Problem — Tile Chessboard Without Two Opposite Corners With Dominoes

Area of a Trapezium (Trapezoid) — Two Ways to Derive the Formula

Area of a Triangle — Formula, Smallest Perimeter Problem

Products of Sines and Cosines (Product to Sum Formulas)