Our teachers were very happy because ______ failed the exam.
A:somebody
B:anybody
C:nobody
已知sin(π6﹣α)=13,则cos2(π3+α)的值是( )
在半径为4cm 的圆中, 挖去一个半径为xcm 的圆面,剩下一个圆环的面积为ycm2,则y与x的函数关系式为( )