※ 引述《yummy100 (LING)》之銘言：
: 1 π/2 sinx
: 8. ∫∫ e dxdy =??
: 0 arccosy
畫積分區域的xy座標圖變換積分順序得
1 π/2 sinx
∫ ∫ e dxdy
0 arccosy
π/2 cosx sinx
= ∫ ∫ e dydx
0 0
π/2 sinx |y = cosx
= ∫ (e )(y) | dx
0 |y = 0
π/2 sinx
= ∫ (e )(cosx) dx
0
sinx |π/2
= e | = e - 1
|0
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