If ƒ(x) = 2x2 + 3, then which of the following represent ƒ(-1)?

Iam guessing c. or d.

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.