Some properties of a regular 11-gon

A regular 11-gon is defined by points [i]A[/i], [i]B[/i], [i]C[/i], ..., [i]J[/i], [i]K[/i]. Diagonals [i]CE[/i], [i]CF[/i], [i]CG[/i], [i]CH[/i], [i]DF[/i], [i]DK[/i] and [i]HK[/i] are drawn. Then intersection points [i]L[/i], [i]M[/i], [i]N[/i] and [i]O[/i] are defined as shown in the figure.[br]Prove the following statements:[br][list][*][i]b[/i]=[i]c[/i],[/*][*][i]d[/i]=[i]e[/i],[/*][*]triangles [i]CLM[/i] and [i]CON[/i] are congruent,[/*][*][i]a[/i]=[i]l[/i] (that is, [i]AB[/i]=[i]DL[/i]).[/*][/list]

Information: Some properties of a regular 11-gon