find diameter of a circle with a portion smaller than a ¼

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<p>Diameter&nbsp;[&nbsp;<b>O</b>&nbsp;]&nbsp;=&nbsp;Length&nbsp;<sub><span style="color: rgb(0,255,127)"><b>&ndash;</b></span></sub>&nbsp;[&nbsp;<span style="color: rgb(0,255,127)"><b>+</b></span>&nbsp;]&nbsp;&sup2;&nbsp;/&nbsp;[&nbsp;4&nbsp;&times;&nbsp;Length&nbsp;<sub><span style="color: rgb(0,255,255)"><b>&ndash;</b></span></sub>&nbsp;[&nbsp;<b>(</b><span style="color: rgb(0,255,255)"><b>&ndash;</b></span><span style="color: rgb(0,255,127)"><b>|</b></span>&nbsp;]&nbsp;]&nbsp;+&nbsp;Length&nbsp;<sub><span style="color: rgb(0,255,255)"><b>&ndash;</b></span></sub>&nbsp;[&nbsp;<b>(</b><span style="color: rgb(0,255,255)"><b>&ndash;</b></span><span style="color: rgb(0,255,127)"><b>|</b></span>&nbsp;]</p>
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