Answer:
Step-by-step explanation:
4 g.
c=42
a=b=d
a+b+42=180
a+a=180-42
2a=138
a=138/2=69
a=69
b=69
c=42
d=69
5a.
a=30
angle O=180-(a+30)=180-(30+30)=180-60=120°
d=80
angle O=180-(d+80))=180-(80+80)=180-160=20°
central angle O of middle triangle=180-(120+20)=180-140=40°
b=c
b+c+40=180
b+b=180-40
2b=140
b=140/2=70
b=70°
c=70°
