Răspuns :
DAB=100
pt ca e patrulater⇒ DAB=DCB=100
ABC=180-DAB=180-100=80
pt ca e patrulater⇒ ABC=ADC=80
pt ca e patrulater⇒ DAB=DCB=100
ABC=180-DAB=180-100=80
pt ca e patrulater⇒ ABC=ADC=80