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Area of the 10 regular polygon is 770cm^2 and the gap between the parallel line is 30,8cm. Find its circumference. Yeah, I'm going to fail on this subject.

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  • $\begingroup$ Do you mean decagon? $\endgroup$ – Bernard Feb 4 '15 at 18:09
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    $\begingroup$ Consider the ten triangles formed by linking each edge to the centre. $\endgroup$ – Joffan Feb 4 '15 at 18:11
  • $\begingroup$ decagon sorry :D $\endgroup$ – naaame Feb 4 '15 at 18:17
  • $\begingroup$ "the gap between the parallel line"? $\endgroup$ – Greg Martin Feb 4 '15 at 18:26
  • $\begingroup$ Yeah.. I really don't know but when I translate it comes out "The gap between the parallel line the sides 30,8 something like that. $\endgroup$ – naaame Feb 4 '15 at 18:29
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Consider the ten triangles formed by linking each edge to the centre as shown:

enter image description here

You should be able to get the base of the triangle from here, then the entire perimeter.

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  • $\begingroup$ Thank you for this! Much appreciate. $\endgroup$ – naaame Feb 4 '15 at 19:27

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