Determine whether the vectors u and v are parallel, orthogonal, or neither.

u = < 10, 6> , v = < 9, 5>
orthogonal
parallel
neither

The dot product here is 10(9) + 6(5)=120
so the vectors are not orthogonal 
u.v = |u| x |v| cos (theta) ; theta is the angle between them 

we know from above that u.v = 120 

|u| = sqrt[10^2+6^2]=11.66
|v| = sqrt[9^2+5^2]=10.29

so we know: 

theta =cos^-1 120/(11.66x10.29)
so theta = 25 degrees