∠AS.AS △OA △qrn O G ∠AS AFn=AQm=k,4Smt△ AF,=k-4 =k()4 ∠F = x=2k、( 两侧轮胎 ∠AS 10/25 合|u10/25 t 2 s s s ' z s s ' z s t t s r ) S n m S k ( n m F k F n Q m k S m S n m S m S n S            = = = = = = = Om ' F z Fz r St Ss Q Q 2 Gu Gs m n GS Gu 2 s t ' z l ) n m 2k ( S F k = =   两侧轮胎