Question 733277
Arc length for central angle θ=20 degrees r=4m 
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find the perimeter:
P = 2(pi)(4m) = 8pi*m
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Arc length if central angle = 20 degrees is 
(20/360)(8pi*m) 
= (1/18)(8*pi*m)
= (4m/9)pi
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Cheers,
Stan H.