Solution Draw a standard projection 100 Determine orientation triangle 110 110 [1]-[110]-[1001 011 011 010 010 11 101 mirror refraction rule 110 110 (101)111 100 ②P<a<zSolution: Draw a standard projection Determine orientation triangle: [111]−[110]−[100] ① initial S.S. mirror refraction rule ② (101)[11 1] P   c ，   F3