问题描述: 求高数二重积分详细题解谢谢 1个回答 分类:数学 2014-12-08 问题解答: 我来补答 ∫∫[D] x*cos(x+y)*dσ=∫[0,π] dx∫[0,x] x*cos(x+y)*dy=∫[0,π] xdx {sin(x+y)|[0,x]}=∫[0,π] [xsin2x-xsinx]dx =-1/2∫[0,π] xdcos2x +∫[0,π] xdcosx=-1/2∫[0,π] xdcos2x +∫[0,π] xdcosx ={-1/2[xcos2x-(xsin2x)/2] +xcosx-sinx} |[0,π]=-3π/2 展开全文阅读