SOLUTION: light bulb of a parabolic reflector is placed at the focus of th reflector for better reflection. suppose that the reflector is 18 inches wide and 10 inches deep what is the eq

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: light bulb of a parabolic reflector is placed at the focus of th reflector for better reflection. suppose that the reflector is 18 inches wide and 10 inches deep what is the eq      Log On


   

Question 1044259: light bulb of a parabolic reflector is placed at the focus of th reflector for better reflection. suppose that the reflector is 18 inches wide and 10 inches deep
what is the equation of the parabola in the parabolic reflector?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Imagine a cross section through the vertex and along the vertical symmetry axis and placed on a cartesian system putting the vertex as a minimum, on the Origin.

If 18 inches wide at top opening, and 10 inches deep, a point on the parabola is (9,10). The "9" because half of x component goes in one direction and the other half goes the other direction.

y=ax%5E2, and use the other one given or described point to find "a".
a=y%2Fx%5E2
a=10%2F81
-
highlight%28y=%2810%2F81%29x%5E2%29


Notice that the question does not involve the focus, although mentioned in the description. The focus can be found.