Answer:
B. 21.64
Step-by-step explanation:
We have been given a triangle and we are asked to find the length of AC (b).
We will use law of cosines to find the length of side AC.

Upon substituting our given values in the formula we will get,
Upon taking square root of both sides of our equation we will be get,
Therefore, the length of b is 21.64 and option B is the correct choice.
Nonlinear negative association
Option A: 
Option C: 
Option F: 
Solution:
Given expression is
.
Option A: 



Hence
is equivalent expression of
.
Option B: 



Hence
is not equivalent expression of
.
Option C: 


(proved in option A)
Hence
is equivalent expression of
.
Option D: 


Hence
is not equivalent expression of
.
Option E: 75
75 is a whole number.
Hence 75 is not equivalent expression of
.
Option F: 


(proved in option A)
Hence
is equivalent expression of
.
Therefore,
are all equivalent expressions of
.
Answer:
Im definitely sure that this is the answer A) 1.8 < 6 < 1.9