Answer:
Answer is E.
Step-by-step explanation:
You can quickly solve this if you know the trig ratio for the special angles. 45 degrees is one of the special angles. In this case you can use the adjacent side and hypotenuse lengths to find s, so cos is the trig ratio you want.
In general:
[tex]cos45 = \frac{1}{\sqrt{2}}[/tex]
The ratio will be the same in this question:
[tex]\frac{1}{\sqrt{2}}= \frac{s}{10 \sqrt{2}}\\1= \frac{s}{10}\\s=10[/tex]
