In D4, let K = {R0, D} and let L = {R0, D, D ', R180}. Show that but that K is not...

In D₄, let K = {R₀, D} and let L = {R₀, D, D ', R₁₈₀}. Show that but that K is not normal in D₄. (Normality is not transitive. Compare Exercise 4, Supplementary Exercises for Chapters 5–8.)