Answer is D - square root of 98
Reason
Using Pythagorean theory to first solve for base diagonal with known legs 5 and 3.
a^2 + b^2 = c^2
5^2 + 3^2 = c^2
25 + 9 = c^2
34 = c^2
Take square root of both sides
5.8 = c
Now find the answer for the diagonal
By using the same formula with known legs 5.8 and 8
5.8^2 + 8^2 = c^2
33.6 + 64 = c^2
97.6 = c^2. Round up to 98
Answer is square root of 98
