ds xtgOdx dΦ=B●d5 =kxcosot·xigOdx =(ktg0)x'cos otdx 中=∫B.d S =(hg)x"cosot dx =(kig0)x'cosot 8= kag0(3x2 Φ1 13 cosot-osintx3) dt ktgOov3t3 sin ot-kigOv3t2 cos ot 3 感生 动生× × × × × × × × × × × × × × × × × × × × ds = xtgdx d B ds    = • = kxcost  xtgdx = (ktg)x costdx 2  =   S B dS   ktg x t dx ktg x t x =    = ( ) cos 3 1 ( ) cos 3 0 2 B  x dx  x y o = ktg v t sint − ktgv t cost 3 1 3 3 3 2 感生 动生 (3 cos sin ) 3 1 2 3 t t x dt dx ktg x dt d =   −    = −