a) b) Hinh 6.5. Xoay trong hong a) Ti/the khdi dau; b) Ti/the cuoi cung. a) b) Hinh 6.6. Xoay ngoai hong a) Ti/the khdi dau; b) the cuoi cung. II. KHOP GOI Duoi - Gap goi: tti 0° den 135° (hinh 6.7) 124