Kąt półpełny ma miarę 180°.
a)
α = 180° - 50° = 130°
β = 180° - 123° = 57°
γ = 180° - 40° = 140°
δ = 180° - (70° + 50°) = 180° - 120° = 60°
b)
α = 90° - 65° = 25°
β = 180° - (140° + 20°) = 180° - 160° = 20°
γ = β + 20° = 20° + 20° = 40°
δ = 180° - (70° + 50°) = 180° - 120° = 60°
