You can break the shape up into a rectangle and a right triangle.
Use your trig ratios to find the missing sides.
Add all the sides up and you have your perimeter!
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<em>*notice how one of the 10 is left out because it is inside the shape so we can't use that to find perimeter.</em>

Hello!
1.
find circumferece
c=2pir
c=2*6*pi=12pi
intercept is 5.4
2pi radians=all
part/whole=part/whole
5.4/12pi=x/2pi
times both sides by 12pi
5.4=6x
divide both sides by 6
0.9=x
answer is 0.9 radians
2.
assuming 9pi/5 radians
find circumference
c=2pir
c=2*26.9*pi
c=53.8pi
arc/circumference=(9pi/5)/2pi
x/(53.8pi)=(9pi/5)/(2pi)
x/(53.8pi)=18/5
times both sides by 53.8pi
x=608.46266 m
about x=608.46 m
Hope this Helps! Have A Wonderful Day! :)