SOLUTION: How do i find the quadratic equation for this: "You're designing a candy bowl that has a circular bottom surface. They want the diameter of the bowl in the opening above to be 12

Question 1159778: How do i find the quadratic equation for this:
"You're designing a candy bowl that has a circular bottom surface. They want the diameter of the bowl in the opening above to be 12 cm and the height of the bowl to be 8 cm. Formulate a quadratic equation that, when rotating around the y-axis, describes a circular bottom surface. You can decide the diameter for the bottom yourself."
I have set the diameter to 2cm and decided that it will rotate from x=1 to x=-1. Shouldn't the equation be y = (x+1)(x-1)???

Answer by MowMow(42) (Show Source): You can put this solution on YOUR website!
No. The parabola has to come below the x-axis to have a circular base.
So lets bring it down below the x-axis to (0,-2) for the vertex.
Then the vertex equation is
y = a(x-h)^2 + k
(h,k) = (0,-2)
and a point the parabola goes through above the x-axis is (6,8)
so 8 = a(6-0)^2 -2
10=36a
a = 10/36 = 5/18
The equation would be: y = (5/18)(x)^2 -2

RELATED QUESTIONS
A kids' organization sold 730 bars last year at $ 2.25 per candy bar. Research has... (answered by CPhill)

(How do you find the surface area of a special rectangular box?) S= 4lw + 2wh (S =... (answered by stanbon)

A circular two tiered wedding cake needs to be frosted. Each tier is 4in high. The bottom (answered by Cromlix)

I have a word problem that I am struggling with again. The probability that San... (answered by richwmiller)

I am trying to figure this out, but I don't know the right equation to use. Owners of a... (answered by stanbon)

A store has candy worth $0.9 a pound and candy worth $1.2 a pound. if the owners want 60... (answered by josgarithmetic)

A store has candy worth $0.90 a pound and candy worth $1.20 a pound. if the owners want... (answered by richwmiller)

Hi- I have a hard time understanding what to do for this problem. Here it is: Find a... (answered by NotGoodAtAlgebra)

I'm not sure where to begin on this. I'm in Algebra II, but I feel like this is more of a (answered by josgarithmetic)