725/1260=0.5754cos∠A=0.5754∠A=54.87°
=arccos(725/1260)=0.957707(弧度) =54.87257(度)725/1260=0.5754cos∠A=0.5754∠A=54.87°
=arccos(725/1260)=0.957707(弧度) =54.87257(度)