Doua unghiuri sunt complementare daca au impreuna 90 de grade. Ca sa gasim complementul unui unghi facem diferenta 90 grade - 15 grade 2' = 89 grade 60' - 15 grade 2' = 74 grade 58'. Iar la celalalt subpunct la fel, 90 grade - 66 grade 12' 23'' = 89 grade 59' 60'' - 66 grade 12' 23'' = 23 grade 47' 37''