Question 1179987
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The circumference of a circle is pi times the diameter; half the circumference is (pi/2) times the diameter.<br>
If that half circumference is 1m, then<br>
{{{(pi/2)(d)=1}}}
{{{d=1/(pi/2)=2/pi}}}<br>
And the answer is as shown by the other tutor.<br>
That answer uses the interpretation that the "semi-circle" being formed is an open figure, consisting of only the curved part of the semicircle.<br>
Another possible interpretation is that the figure being formed is a closed semi-circle, including both the curved part and the diameter.  Of course that will give a different answer.<br>
If the semicircle to be formed is a closed figure, then<br>
{{{(pi/2)d+d=1}}}
{{{((pi/2)+1)d=1}}}
{{{d = 1/((pi/2)+1)}}}<br>
Note that the calculations shown for both interpretations are in meters; since the question asks for an answer in centimeters, you need to do a simple conversion of units.<br>