Consider that the area of a sector of a circle is given by:
where θ is the angle of the sector and r is the radius.
For θ=40 and r = 8cm, you obtain:
The area of the small sector is about 22.34 cm^2.
Now, for θ=320 and r = 8cm, you obtain:
The area of the small sector is about 178.72 cm^2.