Gegeben sei das Dreieck \color{orange}D
.
\displaystyle \int \int_{{\color{orange}D}} f(x,y) \, dA = \ldots
?
\displaystyle
\int_{0}^{X}
\int_{fractionReduce(Y,X,small=true) x - Y}^{-fractionReduce(Y,X,small=true) x +Y}
f(x,y) \, dy dx
\displaystyle
\int_{0}^{X}
\int_{fractionReduce(Y,X,small=true) x - Y}^{-fractionReduce(Y,X,small=true) x +Y}
f(x,y) \, dx dy
\displaystyle
\int_{0}^{X}
\int_{-fractionReduce(Y,X,small=true) x - Y}^{fractionReduce(Y,X,small=true) x +Y}
f(x,y) \, dy dx
\displaystyle
\int_{0}^{X}
\int_{-fractionReduce(Y,X,small=true) x + Y}^{fractionReduce(Y,X,small=true) x +Y}
f(x,y) \, dy dx
\displaystyle
\int_{0}^{X}
\int_{-fractionReduce(Y,X,small=true) x - Y}^{-fractionReduce(Y,X,small=true) x +Y}
f(x,y) \, dy dx
Es ist (z.B.)
{\orange{D}} \subset \mathbb R^2
gegeben durch
{\orange{D}} = \left\{ (x,y) \, | \, 0 \leq x \leq X, \;
fractionReduce(Y,X) x - Y \leq y
\leq -fractionReduce(Y,X) x +Y\right\}
.
Damit schreibt sich dann
\displaystyle \int\int_{\orange{D}} f(x,y) dA =
\int_{0}^{X}
\int_{fractionReduce(Y,X,small=true) x - Y}^{-fractionReduce(Y,X,small=true) x +Y} f(x,y) \, dy dx