Answer: cos(U) = 2/5
Explanation:
cos(x) is equal to the adjacent side length over the hypotenuse.
Let's find the hypotenuse. It is the longest side length and is opposite the right angle: 10.
The adjacent side length is the side right next to the angle U that is not the the hypotenuse: 4.
Simplify the fraction: 4/10 = 2/5