What is the equation of the parabola with a directrix at y = 4 and focus (0, -4).

Given that the directrix is at y = 4 and the focus is at (0, -4), then the vertex is at (h, k) = (0, 0).
p is the distance between the vertex and the focus and between the vertex and the directrix = 4 and since the focus is below the directrix, p is negative, i.e. p = -4
Equation of a parabola is given by (x - h)^2 = 4p(y - k)
Therefore, the required equation is (x - 0)^2 = 4(-4)(y - 0)
x^2 = -16y
y = -1/16 x^2

1)Surface Area of rectangular box=166
2)Surface area= (9*6)+(9*8)+(10*9)+(6*8)=264 square meters
3)45 square ft
4)288.05 square cm
5)S.A of cylinder = 345.6 sq. cm
6)S.A of cylinder = 603.2 sq. ft
7)S.A of cylinder = 276.5 sq.in
8)S.A of cylinder = 353.4 sq. m
9) slant height = 15 inches