量是无穷
幼苗
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记BC为a
(1)2R=a/sin A=c/sin C=b/sin B=4,
∴a=4sin A,b=4sin B
S=1/2*a*bsin C=8sin Asin Bsin C=4√(3)sin xsin (x+π/3)=6sin xcos x+2√(3)sin² x
=3sin 2x+√(3)-√(3)cos 2x=2√(3)sin (2x+π/6)+√3
x∈(0,2π/3)
(2)∵x∈(0,2π/3)
∴2x+π/6∈(0,2π)
∴当2x+π/6=π/2,即x=π/6时
Smax=3√3
1年前
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