Report - cdn035.yun-img.comcdn035.yun-img.com/static/upload/afanedu/download/... · 17. arctan #205}. 18. xdx + ydy ) , r sin 9 4 dÐf arctan dxdy = r cos 9 4 d9f 9rdr= 4 dB -{1,2, x(lnx-+-

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