§1-1欧拉方程 C sin 2 2r c sin Clu=c, cos a=u,-Circtgp C1 Cu=C, cos a=u, -,.ctgB§1-1 欧拉方程 1 1 1 1 1 1 cos ctg u r c c u c = = −   2 2 2 2 2 2 cos ctg u r c c u c = = −   1 1 1 sin r c c =  2 2 2 sin r c c = 