∫∫xy²dxdy=∫dθ∫(rcosθ)*(rsinθ)²*rdr (应用极坐标变换)
=∫(cosθsin²θ)dθ∫r^4dr
=∫sin²θd(sinθ)∫r^4dr
=[(sin³θ/3)│]*[(r^5/5)│]
=(1/3+1/3)*(2^5/5)
=64/15
∫∫xy²dxdy=∫dθ∫(rcosθ)*(rsinθ)²*rdr (应用极坐标变换)
=∫(cosθsin²θ)dθ∫r^4dr
=∫sin²θd(sinθ)∫r^4dr
=[(sin³θ/3)│]*[(r^5/5)│]
=(1/3+1/3)*(2^5/5)
=64/15