Hello! Remember you have to write complete questions in order to get good and exact answers. Here you haven't provided any sector, so I'll help you in a general way and providing my own example.
A sector is a region of a circle between two radii. Suppose you have a central angle [tex]\theta[/tex] degrees, the sector can be found as:
[tex]s=\frac{\theta}{360}\times\pi r^{2}[/tex]
Suppose that the radius of the circle is [tex]4cm[/tex] and the central angle is 90 degrees, therefor the sector is:
[tex]s=\frac{\theta}{360}\times\pi r^{2} \\ \\ s=\frac{90}{360}\times\pi (4)^{2} \\ \\ s=\frac{1}{4}\times 16\pi \\ \\ \boxed{s=4\pi cm^2}[/tex]
