20 points for this one but please with the explanation

Which undefined geometric term is described as a location on a coordinate plane that is designed by an ordered pair (x,y) ?

Weekly wages at a certain factory are normally distributed with a mean of $400 and a standard deviation of $50. find the probability that a worker selected at random makes between $450 and $500

The coordinates r(1, -3), s(3, -1) t(5, -7) form what type of polygon? a right triangle an acute triangle an equilateral triangle an obtuse triangle