In: Advanced Math
A midline is a horizontal line that cuts the graph of the function into two equal parts, or we can say, its a line where half of the function is above it and half of the function is below it.
So simply, to find the midline, we just have to take the arithmetic average of the highest and the lowest value, the function can take.
I've solved for the midline of both the functions and attached a handwrtten solution.