Explain why mathematics is not just a collection of formulas and theorems that people crammed into their head?

What is the range of this function? all real numbers such that y ≤ 40 all real numbers such that y ≥ 0 all real numbers such that 0 ≤ y ≤ 40 all real numbers such that 37.75 ≤ y ≤ 40

Given the graphed function below which of the following orders pairs are found on the inverse function

If the value of cos330°is√3/2 then find cos 165°.