Hello, rtblue!
What is the maximum height that an 8footwide truck can be in order
to pass through a parabolic tunnel that is 18 feet high and 12 feet wide? Code:
(0,18)
*
*  *
*  *
*  *

*  *


*+*
(6,0)  (6,0)

The general equation of a parabola is: .
The parabola passes through three points: .
Substitute these coordinates into the equation:
. .
Solve the system of equations: .
Hence, the parabola is: .
The truck is 8 feet wide.
How high is the tunnel at ?
Code:
18
*
*  *
*  +  *
*  *
  
*   y *
  
  
*+++*
6 4  4 6

At
Therefore, the truck can be 10 feet high (at most).