Răspuns:
Explicație pas cu pas:
Modul 1:
m (∡ A) = 180° - 140°
m (∡ A) = 40°
m (∡ B) = m (∡ C) = (180° - 40°) : 2
m (∡ B) = m (∡ C) = 140° : 2
m (∡ B) = m (∡ C) = 70°
Modul 2:
m (∡ A) = 180° - 140°
m (∡ A) = 40°
m (∡A) = m (∡B) = 40°
m (∡ C) = (180° - 40° x 2) : 2
m (∡ C) = (180° - 80°) : 2
m (∡ C) = 100° : 2
m (∡ C) = 50°