Answer:
Option B. 1.8 seconds
Step-by-step explanation:
h=-16t^2+56t+1
This is a quadratic equation, and its graph is a parabola
h=at^2+bt+c; a=-16, b=56, c=1
Like a=-16<0 the parabola opens downward, and it has a maximum value (height) at the vertex, at the abscissa:

Replacing the known values:

Approximately 1.8 seconds.
Answer: It takes approximately 1.8 seconds the airplane to reach its maximum height.
Answer:
1056.25π square units
Step-by-step explanation:
A few formulas an definitions which will help us:
(1)
, where c is the circumference of a circle and d is its diameter
(2)
, where A is the area of a circle with radius r. To put it in terms of d, remember that a circle's diameter is simply twice its radius, or mathematically, (3)
.
We can rearrange equation (1) to put d in terms of π and c, giving us (4)
, and we can make a few substitutions in (2) using (3) and (4) to get use the area in terms of the circumference and π:

We can now substitute c for our circumference, 65, to get our answer in terms of π:
