Question 1112174
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The circumference of the circle = {{{20pi}}} cm  ====>  the radius of the circle is  r = 10 cm.


The area of a triangle with the perimeter P and the inscribed circle radius r is equal to


Area A = {{{(1/2)*P*r}}}.


    See the lesson
        <A HREF=http://www.algebra.com/algebra/homework/Surface-area/Proof-of-the-formula-for-the-area-of-a-triangle-via-the-radius-of-the-inscribed-circle.lesson>Proof of the formula for the area of a triangle via the radius of the inscribed circle</A> 
    in this site.


In your case the area A = {{{(1/2)*210*10}}} = 1050 sq. cm.
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