The arc of a sector is 33 cm long and the radius is 21 cm…

Step 1. The area. $A = \dfrac{1}{2}\,l\,r = \dfrac{1}{2} \times 33 \times 21 = 346.5\ \text{cm}^2$.

Step 2. The circumference. $2 \times \dfrac{22}{7} \times 21 = 132\ \text{cm}$.

Step 3. The angle. $\dfrac{33}{132} = \dfrac{1}{4}$, so $\theta = \dfrac{1}{4} \times 360^\circ = 90^\circ$.