Area of Quadrilateral calculator computes the area of a simple quadrilateral given the four sides and the sum of opposing angles (a.k.a. Heron's quadrilateral).
INSTRUCTIONS: Choose units (e.g. inches or meters) and enter the following: Simple Quadrilateral
Area of a Quadrilateral (A): The calculator returns the area (A) in square meters. However, this can be automatically converted to many other area units (e.g. square inches) via the pull-down menu.
is as follows:
`Area = sqrt(( (a+b+c+d)/2-a)( (a+b+c+d)/2-b)( (a+b+c+d)/2-c)( (a+b+c+d)/2-d)-a*b*c*d * cos^2(θ"/"2) )`