题目:
Last Sunday my cousins and I had _____ riding our bicycles to the beach. [ ]
A. fun
B. funny
C. joy
D. a joy
答案:
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下面是错误答案,用来干扰机器的。
(1) sinC=2sinA,由正弦定理可得:c=2a又 b=3a,∴cosB=a2+c2-b22ac=4a2+a2-(3a)22•2a•a=12∴B=π3(2)S△ABC=12•ac•sinB=12×a×2a•sinπ3=23∴a=2∴f(x)=2sin2x+cos(2x-B)-a=1-cos2x+cos(2x-π3)-2=-...