Which set of line segments could create a right triangle? A. 5,6, 11
B. 05, 9, 10
C. 5, 13, 18
D. 05, 12, 13

Part A 
7.8 is rational  because it can be written as a fraction 78/100 or 39/50

Part B

7.7^2 = 59.29 and 7.8^2 = 60.84
so an irrational number betwee 7.7 and 7.8 would be  sqrt 60.  Radicals like these ( like sqrt2 , sqrt10 that are not perfect squares)  have irrational square roots).

sqrt 60  = 7.75 to the nearest hundredth

if you try 'square root of 60'on a scientific calculator it usually gives you up to 9 decimal places  Mine gives 7.745966692  but the decimals go on without bounds,