解答题 26.求∫02adx
【正确答案】(0≤θ≤,0≤r≤2a cosθ},则
02adx(x+y)2dy=dθ∫02acosθr3(sinθ+cosθ)2dr
=4a4(1+2sinθcosθ)cos4θdθ
=4a4cos4θdθ+8a4sinθcos5θdθ
【答案解析】