# 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 30-60-90 triangle and the 45-45-90 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 11-gons Dodecagons