a)
AOD=COB=x
AOC=DOB=30
AOD+COB+AOC+COB=360° unghiuri in jurul unui punct
30•2+2x=360
2x+60=360
2x=360-60
x=300:2
x=150
AOD=COB=150°
b)AOD=COB=90+x
AOC=COD=x
AOD+COB+AOC+COB=360° unghiuri in jurul unui punct
(90+x)•2+2x=360
180+2x+2x=360
4x=360-180
x=180:4
x=45°
AOD=COB=45+90=135°
AOC=COD=45°
c) este in poza
d) se rezolva la fel ca astea
