TRONG Δ ABC TA LUƠN CĨA ∠ A+ ∠ B+ ∠ C =900 B. ∠ A+ ∠ B+ ∠ C = 1800...

15/ trong Δ ABC ta luơn cĩ

a A+ B+ C =90

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b. A+ B+ C = 180

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c. A+ B+ C =360

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d. A+ B+ C >180

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