Explanation optional, just need to get this done :P

Answer:
sqrt22/2
Step-by-step explanation:
cos 45 = x/sqrt11
1 / sqrt2 = x /sqrt11
x*sqrt2 = sqrt11
x = sqrt11/sqrt2
Multiply top and bottom of the fraction by sqrt2
x = sqrt11*sqrt2 / 2
= sqrt22/2 (Answer)