If u⋅v>0\mathbf{u} \cdot \mathbf{v} > 0u⋅v>0, the angle θ\thetaθ between the vectors satisfies:
0°<θ≤90°0° < \theta \leq 90°0°<θ≤90°
90°≤θ<180°90° \leq \theta < 180°90°≤θ<180°
θ=0°\theta = 0°θ=0°
0°≤θ<90°0° \leq \theta < 90°0°≤θ<90°