Răspuns:
c)
[tex]\measuredangle7=56^{\circ}[/tex]
d)
[tex]\measuredangle6=\measuredangle4=116^{\circ}[/tex]
Rezolvare:
c)
[tex]\measuredangle1+\measuredangle3=112^{\circ}[/tex]
unghiurile 1 si 3 sunt unghiuri opuse la varf, deci sunt congruente
[tex]\measuredangle1=\measuredangle3[/tex]
[tex]\implies2\measuredangle1=112^{\circ}\implies\measuredangle1=112^{\circ}/2=56^{\circ}[/tex]
ungiurile 1 si 7 sunt alterne externe; deoarece dreptele a si b sunt pararele, unghiurile 1 si 7 sunt egale:
[tex]\measuredangle1=\measuredangle7=56^{\circ}[/tex]
d) Am stabilit deja (vezi subpunctul precedent) ca unghiurile 1 si 3 sunt congruente.
[tex]\measuredangle3=\measuredangle1[/tex]
Unghiurile 1 si 2 sunt suplementare, deci:
[tex] \measuredangle3 = \measuredangle1=180^{\circ}-\measuredangle2[/tex]
[tex]\measuredangle1+\measuredangle2+\measuredangle3=2(180^{\circ}-\measuredangle2)+\measuredangle2=360^{\circ}-2\measuredangle2+\measuredangle2=360^{\circ}-\measuredangle2=244^{\circ}
[/tex]
[tex]
\implies \measuredangle2=360^{\circ}-244^{\circ}=116^{\circ}
[/tex]
Unghiurile 4 si 2 sunt unghiuri opuse la varf, deci sunt congruente:
[tex]\measuredangle4=\measuredangle2=116^{\circ}[/tex]
Unghiurile 4 si 6 sunt alterne interne; pentru ca dreptele a si b sunt paralele, unghiurile 4 si 6 sunt si congruente:
[tex]\measuredangle6=\measuredangle4=116^{\circ}[/tex]