TeachLens

Browse lessons
Algebra
Balancing EquationsSimultaneous EquationsDistributive PropertyFactoring QuadraticsCommon FactorDifference of SquaresFactor by GroupingCompleting the SquareQuadratic FormulasCubic FormulasPower Formulas
Geometry
Area of a Triangle
Trigonometry
SAS Triangle AreaSin, Cos, TanHow Sine Is Derived
Circles
How Pi Is DerivedArea of a CircleArea of a SectorPerimeter of a SectorRadians

Unit circle meaning

Start with a unit circle

radius = 1
radius 1y = sin(theta)x = cos(theta)1 radian1 degreePoint on unit circle(x, y) = (cos(theta), sin(theta))sine is the vertical coordinatesin(1) = sin(1 radian)sin(1 degree) uses a tiny angle~= 0.84147~= 0.01745

A unit circle has radius 1. Put a point on the circle by rotating a radius through an angle theta.