Răspuns :
∡a1+∡a2+∡a3+∡a4=360
∡a1=∡a3=45 (opuse la varf)
∡a2=∡a4
2×45+2∡a2=360
90+2∡a2=360
2∡a2=360-90
2∡a2=270=>∡a2=270:2=>∡a2=135
daca ∡a2=∡a4=>∡a4=135
deci ∡a1=45; ∡a2=135; ∡a3=45; ∡a4=135
(dreptele alea mai sigur sunt concurente in O, nu congruente)
∡a1=∡a3=45 (opuse la varf)
∡a2=∡a4
2×45+2∡a2=360
90+2∡a2=360
2∡a2=360-90
2∡a2=270=>∡a2=270:2=>∡a2=135
daca ∡a2=∡a4=>∡a4=135
deci ∡a1=45; ∡a2=135; ∡a3=45; ∡a4=135
(dreptele alea mai sigur sunt concurente in O, nu congruente)
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concurente si
1=unghiul 1
2=unghiul 2
...................
opuse la vârf =>1=3,2=4
m1=45°=>m3=45°
m1+m2+m3+m4=360°
45°+45°+2m2=360°
90°+2m2=360°
2m2=270°
m2=135°
=>m4=135°
1=unghiul 1
2=unghiul 2
...................
opuse la vârf =>1=3,2=4
m1=45°=>m3=45°
m1+m2+m3+m4=360°
45°+45°+2m2=360°
90°+2m2=360°
2m2=270°
m2=135°
=>m4=135°