# Quadrangle area

A quadrilateral is a polygon with four vertices and four sides. No three vertices of a quadrangle lie on one straight line Distinguish between convex and non-convex quadrangles

.**Area of a quadrangle through diagonals and the angle between them**

**Diagonal of a quadrilateral d1**

**Diagonal of a quadrilateral d2**

**Angle between diagonals α**

The formula for calculating the area of a quadrilateral, through the diagonals and the angle between them:

**S=1/2⋅d1⋅d2⋅sinα∘**

**Area of a quadrilateral through the sides and the corners between these sides**

**Side а**

**Side b**

**Side c**

**Side d**

**Angle between sides α°**

**Angle between sides β°**

Formula for calculating the area of a quadrilateral in terms of its four sides and the angles between these sides:

p – perimeter of a quadrilateral divided by two.