This paper is concerned about two common problems of the square of plane figure and double integral,constructs two different kinds of system of inequalities by skifully using the boundary line,and chooses integration variables and the order of repeated integral quickly and truly on the base of the shape of figures and integrands.
本文针对平面图形面积和二重积分两个常见问题,巧用四条边界线建立两种不同形式的不等式组,同时结合图形形状和被积函数,快速而正确地选择积分变量和累次积分次序,简化了计算,提高了运算能力和解题速度。
A line that establishes or marks a border.
边界线确立或标志边界的线
the boundary line or the area immediately inside the boundary.
直接在边界内部的边界线。
a boundary line between land and water.
陆地与海水的边界线。
the boundary line between two pieces of property.
两块所有地的边界线。
The boundary line of a circle.
圆周一个圆的边界线
Circumference:The boundary line of a circle.
圆周:一个圆的边界线.
A nation has borders or boundaries, and everything within those boundaries belongs to that nation and no other.
一个国家有它的边境或边界线，在边界线内的一切都属于此国。
Curzon Line： Demarcation line between Poland and Soviet Russia.
寇松线:波兰和苏俄之间的边界线。
Sam took the ball from the sideline and threw it towards Justin.
山姆从边界线处把球传给贾斯廷。
Her land frontiers run for 15000 kilometres.
它的陆上边界线长进15000公里。
The extreme edge or margin; a border.
边，边沿，边缘极端的边线或边缘；边沿，边界
Boundary-Pattern Mathematical Programming Nonlinear Multipole Boundary Element Method;
边界型数学规划非线性多极边界元法
"demarcation,also demarkation:The setting or marking of boundaries or limits."
分界线:边界或限制的设定或标记.
The setting or marking of boundaries or limits.
分界线边界或限制的设定或标记
The terminator is the boundary between day and night.
地影界线就是白天和黑夜的边界。
They judge the side lines and the base lines.
他们判断边线和底线球（界内或蜀外）。
The line or frontier area separating political pisions or geographic regions; a boundary.
边境政治划分或地理区域的分隔线或边界；分界线
To set margins, drag the margin boundaries on the rulers.
通过拖动标尺上的页边距界线，可以设置页边距。