Quadrilateral

Cyclic quadrilateral

Cyclic quadrilateral

α + γ = 180 *

β + δ = 180 *

Ptolemy's theorem

e \cdot f = a \cdot c + b \cdot d

Perimeter:

P = 2 \cdot s = a + b + c + d

s = \frac{a + b + c + d}{2}

Area:

A = \sqrt{(s - a) \cdot (s - b) \cdot (s - c) \cdot (s - d)}

Tangential quadrilateral

Tangential quadrilateral

a + c = b + d

Perimeter:

P = 2 \cdot s = a + b + c + d

Area:

A = s \cdot r

Keywords: quadrilateral, cyclic quadrilateral, Ptolemy

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
Basic Proportionality Theorem
The inscribed angle theorem
Triangle
Special Triangles - Right Triangle, Equilateral Triangles, Isosceles Triangles
Quadrilateral
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Analytical Geometry 2D
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