In △ ABC, it is known that ab · AC = - 2 and | ab | · | AC | = 4, then the area of △ ABC is___ ． | Math enthusiast | Mathematical art

In △ ABC, it is known that ab · AC = - 2 and | ab | · | AC | = 4, then the area of △ ABC is___ ．

∵ in △ ABC, we know ab ·ac = - 2, | ab ···ac · = 4, we can get 4 × cosa = - 2, we can get cosa = - 12, | a = 2 π 3. So the area of △ ABC is 12 ×| ab ····ac ·× Sina = 12 × 4 × 32 = 3, so the answer is 3

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