SOLUTION
The shaded part is a sector.
It is one-fourth the area of the whole circle
Area of a circle is given as
[tex]\begin{gathered} \text{Area of a circle = }\pi r^2 \\ \text{where r = radius and from the diagram, the radius = 5} \end{gathered}[/tex]
So, the area of the shaded sector becomes
[tex]\begin{gathered} \text{Area of a sector = }\frac{1}{4}\times area\text{ of a circle } \\ \text{Area of sector = }\frac{1}{4}\times\pi r^2 \\ \text{Area of sector = }\frac{1}{4}\times\pi\times5^2 \\ =\frac{25}{4}\pi \end{gathered}[/tex]
Hence, the answer is
[tex]\frac{25}{4}\pi[/tex]
