Răspuns:
Explicație pas cu pas:
∡AOB + ∡BOC=180°
∡AOB= 40+ BOC
↓
40+∡BOC + ∡BOC =180°
2 ∡BOC =180-40
2∡BOC=140 °
∡BOC=140:2
∡BOC=70°
-
∡AOB= 40+ ∡BOC
∡AOB=40+70
∡AOB=110°
-
b)
∡EOC= 70:2=35
∡COD≡AOB=110° (opuse la varf )
∡EOD= 35+AOB=35+110=145°
-
13)
2x-25+105=180
2x=180+25-105
2x= 180-80
2x=100
x= 100:2
x=50
-
