Răspuns:
Explicație pas cu pas:
suma unghiurilor din jurul unui punct = 360 grade
<AOB+ <BOC+<COA=360
(2X+20)+(3X+10)+(4X+15)=360
9X+45=360
9X=360-45
9X=315
X=315/9
X=35
<AOB=2X+20=2*35+20=70+20=90
<BOC=3X+10=3*35+10=105+10=115
<COA=4X+15=4*35+15=140+15=155
OM bisectoare deci imparte < BOC in 2 unghiuri egale de masura
= 115/2=57 grade 30 min deci <BOM=< MOC=57 grade 30 min
ON bisectoare deci imparte < COA in 2 unghiuri egale de masura
155/2= 77 grade 30 min deci <AON=<CON= 77 grade 30 min
<MON=<MOC+<CON=57 grade 30 min+77 grade 30 min=134 grade 60 min=
135 grade
sau < MON=(<BOC+<COA)/2=(115+155)/2=270/2=135 grade