The area of a trapezoid is the average of the bases times the height, mathematically:
A=h(b1+b2)/2, in this case:
A=3(1.25ft(12in/ft)+14)/2
A=3(29)/2
A=43.5 in^2
16-4=12
12x5=60
I'm putting together assumptions as this isn't really clear to me, I apologize.
Answer:
[Vertex form]
Step-by-step explanation:
Given function:

We need to find the vertex form which is.,

where
represents the co-ordinates of vertex.
We apply completing square method to do so.
We have

First of all we make sure that the leading co-efficient is =1.
In order to make the leading co-efficient is =1, we multiply each term with -3.


Isolating
and
terms on one side.
Subtracting both sides by 15.


In order to make the right side a perfect square trinomial, we will take half of the co-efficient of
term, square it and add it both sides side.
square of half of the co-efficient of
term = 
Adding 36 to both sides.


Since
is a perfect square of
, so, we can write as:

Subtracting 21 to both sides:


Dividing both sides by -3.

[Vertex form]