Traditional Culture Encyclopedia - Photography and portraiture - △ABC, AB=, BC=, AC=, find the area of this triangle, (1) Xiaoming solved this problem by composition method, as shown in figure 1, and established one.

△ABC, AB=, BC=, AC=, find the area of this triangle, (1) Xiaoming solved this problem by composition method, as shown in figure 1, and established one.

Solution: (1) s △ ABC = 3× 3-×1× 2-×1× 3-× 2× 3 = 3.5,

So the answer is 3.5;

(2) As shown in the figure,

,

s△ABC = 4a×2a-×a×2a-×2a×2a-×a×4a = 3a 2 .