Răspuns:
Explicație pas cu pas:
4)
∡AOC=78+100
∡AOC=178°
-
∡MOB= 78:2=39°
∡BON=100:2=50°
∡MON=39+50=89°
-
5)
∡AOB+∡BOC+∡COA= 360°
∡AOB=∡BOC=∡COA=360:3=120°
-
6)
∡AOC=113°
∡BOD=∡AOC=113°(unghiuri opuse la varf)
∡DOA= [ 360-(113+113)]:2= 134:2= 67°
∡AOE = 90°(OE⊥AB)
∡DOE= 67+90
∡DOE= 157°
∡EOC= 113-90
∡EOC=23°
