[TOAN12] Ứng dụng đạo hàm !!!!!!

T

theyang93

viet lai bdt duoi dang: 2(sinA+sinB+sinC)+(tan A+tanB+tanC)>3pi
\Leftrightarrow(2sinA+tan A-3A)+(2sinB+tanB-3B)+(2sinC+tanC-3C)>0
xet hs f(x)=2sinx+tanx-3x tren (0;pi/2)
tacm dk hs dong biển tren khoang tren
vay ta duoc:
2sinA+tan A-3A>0
2sinB+tanB-3B>0
2sinC+tanC-3C>0
cong ve voi ve ta dc dieu can cm:)>-
 
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