Geometry & Trig Reference
Math formulas, definitions, properties, diagrams and examples from Geometry and Trigonometry
Geometry Stuff  
Perimeters  Areas 
Circle Stuff  
The Geometry of Circles: Definitions and formulas for the radius of a circle, the diameter of a circle, the circumference (perimeter) of a circle, the area of a circle, the chord of a circle, arc and the arc length of a circle, sector and the area of the sector of a circle 
The Trigonometry of Circles: Definitions and formulas for the arc and the arc length of a circle, sector and the area of the sector of a circle, the unit circle, the angles on the unit circle in radians, the angles on the unit circle in degrees, the points on the circumference of the unit circle 
Triangle Stuff  
Notations: Geometry notations for triangles including the right triangle, congruent sides of a triangle and congruent angles of a triangle 
The Geometry of Triangles: Definitions and formulas for the area of a triangle, the sum of the angles of a triangle, the Pythagorean theorem, Pythagorean triples and special triangles (the 306090 triangle and the 454590 triangle) 
Types of Triangles: Definitions and formulas for triangles including right triangles, equilateral triangles, isosceles triangles, scalene triangles, obtuse triangles and acute triangles 
The Trigonometry of Triangles: Definitions and formulas for basic trigonometry, sine, cosine, tangent, cosecant, secant, cotangent, the law of sines and the law of cosines 
Quadrilateral Stuff: Definitions and formulas for perimeter and area, properties of sides and angles, diagrams 

Squares  Rhombuses (Rhombi) 
Rectangles  Kites 
Parallelograms  Trapezoids 
Properties of Polygons: Information on properties, interior angles and central angles 

Triangles  Quadrilaterals  Pentagons 
Hexagons  Heptagons  Octagons 
Nonagons  Decagons  11gons 
Dodecagons 