Which one is it? is it a. b. c. or d.?

The pie is multyplued by the second step

Whose mistake? can you give more details to what the question is asking?

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.