The area of a sector of a circle of radius 2 cm

We know that the area A of a sector of an angle θ in the circle of radius r is given by

$A=\frac{\theta}{360^{\circ}} \times \pi r^{2}$

It is given that $r=2 \mathrm{~cm}$ and area $A=\pi \mathrm{cm}^{2}$.

Now we substitute the value of r and A in above formula to find the value of θ,

$\pi=\frac{\theta}{360^{\circ}} \times \pi \times 2 \times 2$

$\theta=\frac{360^{\circ} \times \pi}{\pi \times 2 \times 2}$

$=90^{\circ}$