For a piece of land as shown in the figure, ad = 12M, CD = 9m, ∠ ADC = 90 °, ab = 39m, BC = 36m, calculate the area of this land

For a piece of land as shown in the figure, ad = 12M, CD = 9m, ∠ ADC = 90 °, ab = 39m, BC = 36m, calculate the area of this land


If AC is connected, in RT △ ADC, ac2 = Cd2 + ad2 = 122 + 92 = 225, х AC = 15; in △ ABC, AB2 = 1521, ac2 + BC2 = 152 + 362 = 1521, х AB2 = ac2 + BC2, х ACB = 90 degree, х s △ abc-s △ ACD = 12ac · bc-12ad · CD = 12 × 15 × 36-12 × 12 × 9 = 270-54 = 216