The buttonhole size needed to fit the button is 3cm.
The solution is as follows: Solve for d when C = 9.42 cm=2πr d = 2r r = C/2π = 9.42 / 2π r = <span>1.49923956393 d = 2(</span>1.49923956393) = <span>2.99847912785 or <span>3cm
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