Since it is a right triangle, we can apply trigonometric functions:
Cos a = adjacent side / hypotenuse
a = angle = 45
Adjacent side = x
Hypotenuse = √5
Replacing:
Cos 45 = x / √5
Solve for x
Cos 45 (√5) = x
√2/2 (√5) = x
√10/2 = x
[tex]x=\frac{\sqrt[]{10}}{2}[/tex]
