Answer:
<h2>89.5°</h2>
Step-by-step explanation:
Using the vector formula 
|u| = magnitude of vector u
|v| = magnitude of vector v
u.v is the dot product of vector u and v
Given |u| = 88, |v| = 99 and u.v = 77, to get
we will substitute the given values into the equation above;

1279???
Because the gcf does not leave any remainders behind. The gcf could be 1280, but that would not leave a remainder behind if you divided 1280 by 1280. So, I think it is 1279, but i am probably wrong