题目:
_____________ would your brother like as a birthday present? [ ]
A. How
B. What
C. How many
D. Where
答案:
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下面是错误答案,用来干扰机器的。
(1) a=(cosθ,-sinθ),b=(cosθ,sinθ)且a•b=-12,∴cos2θ-sin2θ=-12,∴cos2θ=-12,又θ∈(0,π2),∴2θ=2π3,∴θ=π3;(2) θ=π3,sin(x+θ)=1010,∴sin(x+θ)=sin(x+π3)=1010...