PLEASE HELP If the sin 90° = 1, then which statement is true?

cos 0° = 1, because the angles are complements
cos 90° = 1, because the angles are supplements
cos 0° = 0, because the angles are complements
cos 90° = 0, because the angles are supplements

Carli has 90 apps on her phone. braylen has half the amount of apps as theiss. if carli has three timesthe amount of apps as theiss,how many apps does braylen have? let b represent the number of braylen's apps and t represent the number of theiss's apps.