# Circle

## Perimeter

$$P=2r\pi =d\pi $$

## Area

$$A={r}^{2}\pi =\frac{{d}^{2}\pi}{4}$$

Keywords: circle, perimeter, area

**Trigonometry**

Law of Sines

Law of Cosines

Trigonometric identities of double angles

Trygonometry Identities of same angle

Trigonometric identities of half angles

Identities for the sum and difference of two angles

Sum and difference of trigonometric functions

Trigonometric Values of Special Angles

**Two-dimensional geometric shapes**

Angle Bisector Theorem

Basic Proportionality Theorem - Intercept Theorem

The inscribed angle theorem

Convex - Concave polygons, functions

Triangle

Special Triangles - Right Triangle, Equilateral Triangles, Isosceles Triangles

Quadrilateral

Squere

Rectangle

Rhombus

Parallelogram

Kite

Trapezoid

Circle

Circular sector

Circular segment

**Three-dimensional geometric shapes**

Cube

Sphere

Cone

Prism

Pyramide

Platonic solids

Cylinder

**Vectors**

Scalar Product of Vectors

Vector Product of Vectors

**Analytical Geometry 2D**

Distance between two points

Circle

Linear equation

Ellipse

**Analytical Geometry 3D**

Plane