View Compilation Error

1_218_765_14522.cpp
1_218_765_14522.cpp(6) : error C2668: “acos” : 对重载函数的调用不明确
        VC\include\math.h(586): 可能是“long double acos(long double)”
        VC\include\math.h(538): 或       “float acos(float)”
        VC\include\math.h(183): 或       “double acos(double)”
        试图匹配参数列表“(int)”时