Answer:
C. 647 square units
Step-by-step explanation:
To find the shaded area, subtract the area of the unshaded square from the area of the octagon.
<u>Area of the octagon</u>

where:
- n = number of sides
- l = length of one side
- a = apothem
Given:
Substitute the given values into the formula and solve for A:



<u>Area of the square</u>

<u>Area of the shaded region</u>
= area of the octagon - area of the square
= 815.88 - 169
= 646.88
= 647 square units (nearest square unit)
Answer:
the answer s hard
Step-by-step explanation:
Factoring:
Theory : A difference of two perfect cubes,
can be factored into

Proof : 




Check : 8 is the cube of 2
Check : 27 is the cube of 3
Check :
is the cube of
Check :
is the cube of 
Factorization is :

I think it is 21+10=31...