D={(r,θ)∣3≤r≤5,3π4≤θ≤5π4}D = \bigg\lbrace (r, \theta)|3 \le r \le 5, \frac{3\pi}{4} \le \theta \le \frac{5\pi}{4}\bigg\rbraceD={(r,θ)∣3≤r≤5,43π≤θ≤45π}