可否证明: tan(arctan(a))=tan(arctan(b)+arctan(c))tan(arctan(a)) = tan(arctan(b) + arctan(c))tan(arctan(a))=tan(arctan(b)+arctan(c)) 当 arctan(a)=arctan(b)+arctan(c)arctan(a) = arctan(b) + arctan(c)arctan(a)=arctan(b)+arctan(c)
