高数曲面总结 第1篇
(1)Stokes公式,是Green公式的推广,主要表达了三维空间的曲线积分与曲面积分之间的互相转换,行列式表达的公式如下:
\iint_{\Sigma}\left | \begin{matrix} dydz &dzdx & dxdy \\ \frac{\partial}{\partial x} &\frac{\partial}{\partial y} & \frac{\partial }{\partial z} \\ P &Q & R\end{matrix} \right |=\oint_{\Gamma}Pdx+Qdy+Rdz
\iint_{\Sigma}\left | \begin{matrix} cos\alpha &cos\beta & cos\gamma \\ \frac{\partial}{\partial x} &\frac{\partial}{\partial y} & \frac{\partial }{\partial z} \\ P &Q & R\end{matrix} \right |dS=\oint_{\Gamma}Pdx+Qdy+Rdz
(2)空间曲线积分与路径无关的条件: \frac{\partial P}{\partial y }=\frac{\partial Q}{\partial x} , \frac{\partial Q }{\partial z }=\frac{\partial R}{\partial y} , \frac{\partial R}{\partial x }=\frac{\partial P}{\partial z}
(3)环流量,是向量场 A 沿有向闭曲线 \Gamma 的环流量:
\oint_{\Gamma}\bm A\cdot\bm \tau ds=\oint_{\Gamma}\bm A\cdot d\bm r=\oint_{\Gamma}Pdx+Qdy+Rdz =\iint_{\Sigma}\left | \begin{matrix} dydz &dzdx & dxdy \\ \frac{\partial}{\partial x} &\frac{\partial}{\partial y} & \frac{\partial }{\partial z} \\ P &Q & R\end{matrix} \right |
=\iint_{\Sigma}\left | \begin{matrix} cos\alpha &cos\beta & cos\gamma \\ \frac{\partial}{\partial x} &\frac{\partial}{\partial y} & \frac{\partial }{\partial z} \\ P &Q & R\end{matrix} \right |dS
(4)旋度: \bm r\bm o\bm t\bm A= \left | \begin{matrix} \bm i &\bm j & \bm k \\ \frac{\partial}{\partial x} &\frac{\partial}{\partial y} & \frac{\partial }{\partial z} \\ P &Q & R\end{matrix} \right |
曲线与曲面积分的公式与知识点总结就到这里结束了……
高数曲面总结 第2篇
(1) Gauss公式,表达了三维空间中闭合区域上的三重积分与其边界曲面上的曲面积分的互相转换,即三维空间的三重积分与第一类曲面积分、第二类曲面积分之间的互相转换:
\iiint_{\Omega}(\frac{\partial P}{\partial x}+\frac{\partial Q}{\partial y}+\frac{\partial R}{\partial z})dv=\oint_{\Sigma} Pdydz+Qdzdx+Rdxdy
\iiint_{\Omega}(\frac{\partial P}{\partial x}+\frac{\partial Q}{\partial y}+\frac{\partial R}{\partial z})dv=\oint_{\Sigma} (Pcos\alpha+Qcos\beta+Rcos\gamma)dS
(2)沿任意闭曲面的曲面为 0 的条件: \frac{\partial P}{\partial x}+\frac{\partial Q}{\partial y}+\frac{\partial R}{\partial z}=0
(3)向量场: \bm A(x,y,z)=P(x,y,z)\bm i+Q(x,y,z)\bm j+R(x,y,z)\bm k
(4)通量,向量场通过曲面指向侧的通量:
\iint_{\Sigma}\bm A\cdot \bm ndS= \iiint_{\Omega}(\frac{\partial P}{\partial x}+\frac{\partial Q}{\partial y}+\frac{\partial R}{\partial z})dv=\oint_{\Sigma} Pdydz+Qdzdx+Rdxdy
=\oint_{\Sigma} (Pcos\alpha+Qcos\beta+Rcos\gamma)dS
(5)散度: div\bm A=\frac{\partial P}{\partial x}+\frac{\partial Q}{\partial y}+\frac{\partial R}{\partial z}
高数曲面总结 第3篇
①第一类曲线积分是对弧长的曲线积分,是定义在二维空间或三维空间的曲线的积分,下面是对二维空间弧长曲线积分的计算法
\begin{cases} x=\varphi (t) \\ y=\psi(t) \end{cases} , (\alpha\leq t \leq\beta)
\int_{L}f(x,y)ds=\int_{\alpha}^{\beta}f[\varphi(t),\psi(t)]\sqrt{\varphi^{'2}(t)+\psi^{'2}(t)}dt
②第二类曲线积分,是分别对坐标 x,y 的曲线积分,也是定义在二维空间或三维空间的曲线积分,对坐标的曲线积分的计算法如下
\int_{L}P(x,y)dx+Q(x,y)dy=\int_{\alpha}^{\beta} P[\varphi(t),\psi(t)]\varphi^{'}(t)+Q[\varphi(t),\psi(t)]\psi^{'}(t)dt
③两类曲线积分之间的联系,可以通过方向余弦联系起来,设 \alpha,\beta,\gamma 为有向曲线弧在三维空间的点 (x,y,z) 处的切向量的方向角,那么联系如下:
\int_{\Gamma}Pdx+Qdy+Rdz=\int_{\Gamma}(Pcos\alpha+Qcos\beta+Rcos\gamma)ds