用于前方交会的计算，已知两点及两测站观测角值，在相关提示下，可将输入的度分秒值，求出未知点坐标。并作毫米级检核。-Used for the calculation of forward intersection, known to two points and two station observation angle value, in the relevant prompt can be entered degrees minutes and seconds values, the unknown point coordinates are obtained. And for mm-level check.