by Guest » Sat May 21, 2005 9:28 pm
You need to specify the angles in the corners as well as the lengths of the sides. Alternatively, you can specify both the length and the bearing angle of each of the four sides (usually available from the deed) and calculate it.
The minimum is to know the four sides and any one angle (you have to know which sides the angle is between). You can calculate the diagonal opposite the angle using the law of cosines. Now the lot is divided into two triangles, each with all three sides known, and the area is easily calculated using Heron's formula, or other methods.