The x-coordinate (or t-coordinate) of the vertex is 1.5 and represents how long the football has been in the air at its peak.
The y-coordinate (or h-coordinate) of the vertex is 36 and represents the football's height at its peak.
In Mathematics and Geometry, the maximum value of any function is a point on the graph where the function reaches its highest point. Additionally, the maximum value of Brett's quadratic function can be determined by finding the axis of symmetry;
Axis of symmetry, x = -b/2a

where:
a = -16, b = 48, and c = 0.
By substituting the values of a and b into the formula, we have;
Axis of symmetry, x = -48/2(-16)
Axis of symmetry, x = 48/32
Axis of symmetry, x = 1.5 hour.
Now, we can determine the maximum value (vertex) as follows;

h(1.5) = 36 feet.