Fx=F1+Fa cos45+F cos450 g" (2+2)q =4T.l2 +及 812 = 2 8元e.l2 同理 Fy=F2= (2+2)q 8Te.12 F=F+rP=r q F,=12TE12 F与F,的方向余弦 1 cosa=cosB=cos Y= N3 题号结束45 0 Fx = F1+F4 cos 45 0 +F6 cos 2 = × × 2 π + q l 4ε 2 0 2 π q l 8ε 2 0 2 2 = 2+ 2 q 2 π l 8ε 2 0 ( ) F′ = Fx Fy +Fz 2 + 2 2 = 3 Fx 2 F7 = π q l 12 ε 2 0 2 F′与F7的方向余弦 cosa = cosβ = cosγ= 3 1 Fy = Fz = 2+ 2 q 2 π l 8ε 2 0 ( ) 同理 题号 结束