Hello! Please help me on this question! I know how to do it but I don't know what is the purpose of finding the critical point. What does it offer? Also, why do we just change the distance formula into a function and do partial derivative on it? I am really confused but I still know how to do it by using formulas, I am so lost by the definition. I really need some help with this question for the very very detailed explanation. :'(

Find the points on the cone 22 = 132 + ya that are closest to the paint {-2,4,0}