Question 1041774
What I say here is help, but is not a complete answer.


The "base" would be the vertex for a parabolic cross section.  Imagine or sketch a parabola concave upward with vertex at the origin (0,0), and focus at  (0,1).  There is a directrix which should be understood to be  (0,-1).


Are you familiar with how to derive the equation for a parabola if the focus and directrix are given as known?  If you know how, then find this equation.  Use it to find the unknown coordinate of the point on the parabola,  (u,6).  Recall from the description, the flashlight is 6 cm deep.  The width at the opening will be {{{2u}}}.