a)Daca,un,unghi,are,40°=>si,unghiul,opus,este,tot,40°.
Celelalte,doua,unghiuri,opuse,si,congruente,au,masura,fiecare,de,(360°-80°)/2=140°.
b)Daca,suma,a,doua,unghiuri,opuse,si,congruente=234°=>fiecare,are,masura,de,234°:2=117°
=>Celelalte,doua,unghiuri,opuse,si,congruente,au,masura,fiecare,de,
(360°-234°)/2=126/2=63°
c)Doua,unghiuri,alaturate,sunt,suplementare,adica,insumate=180°
Daca,a+b=180,si,a-b=38=>a=109°,si,b=71°
d)Daca,a+b=180,si,a/b=4=>a=4b,si,5b=180=>b=36°,si,a=144°
e)Daca,a+b=180,si,a=80b/100=8b/10=4b/5
4b/5+b=180
4b+5b=900
9b=900
b=100°
a=80°