question: Below is the graph of a trigonometric function. It has an amplitude of 1.8 . What is the midline equation of the function?
query_wo: Please directly answer the question and provide the final value, e.g., 1, 2.5, 300.
  Question: Below is the graph of a trigonometric function. It has an amplitude of 1.8 . What is the midline equation of the function?
query_cot: Please first conduct reasoning, and then answer the question and provide the final value, e.g., 1, 2.5, 300, at the end.
  Question: Below is the graph of a trigonometric function. It has an amplitude of 1.8 . What is the midline equation of the function?
question_for_eval: Below is the graph of a trigonometric function. It has an amplitude of 1.8 . What is the midline equation of the function?