单项选择题
若D是以(0,0),(1,1),(0,1)为顶点的三角形,则二重积分等于:()
A.e-1 B.1-e C.(1/2)(e-1-1) D.(1/2)(1-e-1)
A.0 B.-2 C.2 D.4
A.f(rcosθrsinθ)rdr B.f(rcosθ,rsinθ)rdr C.f(rcosθrsinθ)rdr D.f(rcosθ,rsinθ)rdr