Give the possible measure for the third side of a triangle if the other two sides are 7 and 11?

Which 2 sides ? 
Pythagorean Theorem = a^2 + b^2 = c^2 

which side do you need? 

The hypotenuse is the longest side. 

for example 7^2 + 11^2 = c^2 
then 
49 + 121 = 170 

Therefore, the answer is the square root of 170. 

But you may have 
7^2 + b^2 = 11^2 which would be 49 + b^2 = 121 

so b would be the square root of 72 

Can you show me the exact problem??

The answer is the third choice