{(-1,2), (5,6), (4,8), (5,7), (-3, 4)} is this a function?

What is the point of inflection for the function f(x)=2cos4x on the interval (0, pi/2)

What is the measure of each of the two angles formed by the bisector of the diagonal of a rhombus if the original angle measures 58 degrees?

An airplane is flying at an elevation of 5150 ft, directly above a straight highway. two motorists are driving cars on the highway on opposite sides of the plane, and the angle of depression to one car is 35 ̊ and to the other is 52 ̊. how far apart are the cars?