A home satellite dish is 56 cm across and 7 cm deep. The cross-section is parabolic in shape.
What is the quadratic function that describes this shape of the cross-section of the dish?
center the vertex at 0, 0
vertex form becomes
y = a ( x-0)^2 + 0
y = a x^2 now sub in the points given
7 = a (28)^2 ( 28 is 1/2 of the 56 dimension)
7/784 = a
y = 7/784 x^2
Here is the graph: (just the graph between the blue dots)