如图,等边三角形OAB的顶点O在坐标原点,顶点A在x轴上,OA=2,将等边三角形OAB绕原点顺时针旋转105°至OA′B′的位置,则点B′的坐标为
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A. Take turns.
B. Keep your desk clean.
C. Work quietly.
D. Talk quietly.
E. Keep to the right.
已知tanαtanα-1=﹣1,求下列各式的值:
(1)sinα-3cosαsinα+cosα;
(2)sin2α+sin αcos α+2.
目前困扰核电站发展的主要问题是()