Can we get some answer choices?
There are six possible outcomes and one favourable event (2 is the only one even prime number), so the probability is

.
Using the Pythagorean theorem:
a^2 + b^2 = c^2
A and B are the sides and c is the hypotenuse.
4^2 + 5^2 = c^2
Simplify:
16+25 = c^2
41 = c^2
Take the square root of both sides:
c=√41