Area of a polygon

The area command finds the area of a circle or a star-shaped polygon.

area takes P, a circle or polygon which is star-shaped with respect to its first vertex (i.e., the line segment from the first vertex to any point in the polygon lies within the polygon).
area(P) returns the area of P.

area(triangle(0,1,i))

area(square(0,2))

The area command has areaat and areaatraw versions (see Section 26.13.1).