Write a possible explicit rule for the nth term of the sequence 23.1, 20.2, 17.3, 14.4, 11.5, 8.6

Ithink it’s b because it say 3 plastic rings and all the balls

Hello! i hope this
since the cosine is the ratio of the adjacent side to the hypotenuse, you can see that cos 60° = ½. answer. according to the property of cofunctions (topic 3), sin 30° is equal to cos 60°. sin 30° = ½.