Answer:
Volume = 1114.1 
Step-by-step explanation:
Recall that the formula for the volume of a pyramid is given by:

where B is the area of the pyramid's base (in our case a square of side 12,8 in), and H the pyramid's height (in our case 20.4 in).
Then the square base of the pyramid has an area given by: 
Finally,we can now write the volume of the pyramid as:

Rounding the answer to a tenth of a cubic inch, we get:
Volume = 1114.1 
Answer: F
In scientific notation, there is one number to the left of the decimal point
Since the decimal point was moved four places to the right, the exponent is a negative 4
Answer:
138 is the answer
Step-by-step explanation:
In order to find the perimeter, we use this formula
P=2(l+w)
And to find the width, we use this formula
w = P/2 - L = 18/2 - 3 = 6
So the width is 6
3 × 6 = 18
So thats why the perimeter of the top triangle is 18
We do 21 ÷ 3 = 7, 7 = scale factor
To find the perimeter of the bottom triangle, we do
the width of the top rectangle times 7
so 6 × 7 = 48
So the perimeter for the bottom triangle is
P=2(l+w)=2·(48+21)=138