Answer:
19.0 cm (3 sf)
Step-by-step explanation:
Formula
[tex]\sf arc \ length=2\pi r \left(\dfrac{\theta}{360}}\right)[/tex]
(where r is the radius)
Arc length of white sector
Radius of white sector = 8 - 4.5 = 3.5 cm
[tex]\sf \implies arc \ length=2\pi \cdot 3.5 \left(\dfrac{50}{360}}\right)=\dfrac{35}{36} \pi \ cm[/tex]
Arc length of grey sector
Radius = 8 cm
[tex]\sf \implies arc \ length=2\pi \cdot 8 \left(\dfrac{50}{360}}\right)=\dfrac{20}{9} \pi \ cm[/tex]
Perimeter of shaded part
Perimeter = arc length (white) + arc length (grey) + 2 x 4.5
[tex]\sf =\dfrac{35}{36} \pi + \dfrac{20}{9} \pi +9[/tex]
[tex]\sf =19.0356432...[/tex]
[tex]\sf =19.0 \ cm \ (3 \ sf)[/tex]
