易安居士_zhang
幼苗
共回答了28个问题采纳率:89.3% 举报
设所求积分为I,
P'y=e^x cosy-my,Q=e^xcosy-m,
P'y=-siny*e^x-m,Q'x=e^x*cosy,
根据格林公式,I+∫[OA弧]=∮[OALO] [(e^x cosy-my)dx+(e^xcosy-m)dy]
=∫[D}∫[e^x*cosy-(e^xcosy-m)]dxdy
=m∫∫dxdy
=m∫[0,π/4] ∫[0,cos2θ)rdrdθ
=mπa^2/8,
∵OA方程为y=0,
dy=0,
∫[OA](e^x cosy-my)dx+(e^xcosy-m)dy=0,
∴I=πma^2/8,
1年前
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