Find the perimeter of the shaded area

Answer:
Step-by-step explanation:
TOTAL area of the entire circle would be pi r^2
= 81 pi cm^2
this is a fraction of the total
72 pi / 81 pi * 360° shows that x = 320°
Perimeter of entire circle is pi * d = 18 pi
thus the curved perimeter is 320 / 360 * 18 * pi = 16 pi
now add the two 9cm radii for a total perimeter of 16 pi + 18 = 62.3 cm