This agreement is very a____(模棱两可的) and open to various interpretations.
设△ABC的内角A、B、C所对的边分别为a、b、c,已知a=1,b=2,cosC=14
求△ABC的周长
计算:﹣4×﹣(﹣2)的结果是( )
2(xy+13y2)−13(2y2+7yx)−3 ,其中 x=−1,y=2