He diagram below represents the circle inside a wrestling mat.

the approximate area of the circle is—

select one:
a. 1,384.74 ft2
b. 263.76 ft2
c. 5,538.96 ft2
d. 131.88 ft2

A. 1,384.74 ft2

Step-by-step explanation:

to formula for area of a circle is π × r2

r2 in here is represents the radius

if we take π as 3.14 then

21^2 × 3,14 = 1,384.74 ft2

It is the first choice.

Step-by-step explanation:

This is a sequence where

the next term is obtained by adding 6.

first term = -9 + 6(0) = -9

second term = -9 + 6(1) = -3

third term = -9 + 6(2) = 3

4th term = -9 + 6(3)  = 9  

and 81 = -9 + (6*15).

So the answer is  Sigma (-9 + 6n)  from n= 0 to n = 15.