Answer:
(a)Vertex
(c)3 seconds
Step-by-step explanation:
Part A
The maximum point on a parabola is called the Vertex.
Part C
To find out how much the plain was in the air, find the values of t at which the height, h=0.
Next, subtract the second value of t from the first value.
First, set h=0:
Factorize:
Therefore, the plane hits the ground after 3 seconds.