Multiply the lengths of the sides if you need to calculate the area of a square or rectangle. If you want to know the area of a right triangle, extend it to a rectangle to calculate its area and divide it into two.
Use to compute the area of polygons the following method, if the shape has interior angles greater than 180 degrees (a convex polygon), and all its vertices are in the mesh nodes coordinates and polyline itself does not cross.
Describe around such a polygon rectangle so that its sides were parallel to the grid lines (coordinate axes). At least one of the vertices of the polygon must be a vertex of a rectangle.
Divide the space inside the rectangle in the basic shapes (triangles and squares). Find the area of each and add up all the resulting squares. Subtract the area of the rectangle calculated square inner shapes. So you will find the area of a polygon fast enough.
Use one of the following formulas to calculate the area of a regular polygon (angles and sides are equal):

– multiply the number of corners (sides) of the polygon n at two radius r of the inscribed circle and the tangent (π/n);

– multiply (n/2) for two radius R of the circumscribed circle and the sine (2π/n);

– multiply (n/4) for two radius r of the incircle and the cotangent (π/n).
Use the following formula, when known side of the triangle:

– multiply the side of the triangle that are adjacent to the corner C, the sine of this angle;

– subtract properiety (p) of the triangle first, one side (p-a), then the other (p-b) and third (p-c). Multiply the values obtained with pauperisation and divide the result by 2.
Use to find the area of a trapezoid the formula S = h * ( a + b ) / 2, if we know the height and both bases of the trapezoid.
Use a method of calculating square of polygon with the help of palettes. Draw a polygon around the square grid, in which the side of one cell will be equal to one for all vertices of the polygon were located in the nodes.
Calculate the area of this figure by the formula of Peak: S = B + G/2 – 1. Here is the number of grid points located inside the polygon, and G is the number of nodes of a square grid located at the border of the polygon.