0∘<θ<90∘0^{\circ}<\theta<90^{\circ}0∘<θ<90∘
0∘≤θ<90∘0^{\circ} \leq \theta<90^{\circ}0∘≤θ<90∘
90∘<θ≤180∘90^{\circ}<\theta \leq 180^{\circ}90∘<θ≤180∘
90∘≤θ≤180∘90^{\circ} \leq \theta \leq 180^{\circ}90∘≤θ≤180∘