The square footage of that shape can be found by dividing the lot into two triangles, finding the area of each, then adding up the two areas.
Triangle 1 - right angle triangle sides 78 and 225
Area = height x base / 2 = 225*78/2 = 8,775 ft2
Next we need to find the length of the diagonal line which is the the hypotenuse D of the right angle triangle:
D^2 = 225^2 + 78^2 = 50,625 + 6,084 = 56,709
D = SQRT(50,709) = 238.14 ft
Since we now have the 3 sides, i.e. 125, 213. and 238.14, the area can be found using the triangle area formula:
(Area)² = s(s-a)(s-b)(s-c) where s=(a+b+c)/2
Applying this formula, the area of triangle 2 is 13,269.36 ft2
Therefore total area of plot = 8,775 + 13,269.36 = 22,044.36 square feet.
Hope this helps.