It's a function because each input has one output
Answer:
=

Step-by-step explanation:
Given:
Length of butcher paper,(diameter of three congruent circle) = 21 inches
Means, diameter of a circle =
= 7 inches
Questioned asked:
Area of one circle = ?
Solution:
Radius of a circle ,r = half of of one circle's diameter
r = 
= 
Area of circle = 


=

Therefore, Area of one circle ==

Special cases of the sum and difference formulas for sine and cosine yields what is known as the double‐angle identities and the half‐angle identities.
It is B that your looking for