You can put this solution on YOUR website! Please put arguments to functions in parentheses. What you posted meant:
but you might have intended:
Without the parentheses we can't tell the difference.
The midline of a sin function is a horizontal line. The equation of all horizontal lines have the form:
y = number
The midline of the first equation above is y = 1/2
The midline of the second equation above is y = 0