ll. The consequence of rotation 1. Change in length of the specimen ① n tension L=1+y(l·n)b L=I1+2y cos A cos o+r2 cos2 o L Xb sin Aon cos sin n ② In compression A=a-y(a·b)n◆ Ⅲ.The consequence of rotation : 1. Change in length of the specimen      2 2 L = l 1+ 2 cos cos + cos ① In tension L l l n b       = + (  )     cos cos sin sin 0 0 l L b   n   ② In compression A a a b n       = − (  )