Punctul a)
Unghiul din imagine îl putem citi astfel:
[tex]\tt \measuredangle AOB, \measuredangle BOA, \measuredangle EOB, \measuredangle BOE, \\ \measuredangle AOF, \measuredangle FOA, \measuredangle EOF, \measuredangle FOE, \measuredangle O[/tex]
În 9 moduri putem citi unghiul.
Punctul b)
[tex]\tt A,E,F,B \in \measuredangle O\\ \tt C,H \in Int \measuredangle O\\ \tt D,G \in Ext \measuredangle O[/tex]