The value of DE is 6.8
To determine the value of the length, we have that;
Using the cosine identity, we have;
cos 65 = x/11
cross multiply the values, we get;
x = 11cos 65
x = 11 × 0. 422
x = 4. 6
Now, to determine the value of the side DE, we have;
Using the Pythagorean theorem, we get;
DE²= 5² + 4.6²
DE² = 25 + 21. 4
add the values
DE² = 46. 4
Find the square root
DE = 6.8