One side of a triangle is divided into segments of length 
<i>a</i> and <i>b</i> by the inscribed circle, with radius <i>r</i>.
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Prove that the area is: 



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&#x00A0;<i>abr</i>(<i>a</i>+<i>b</i>)
<div class="hrcomp"><hr noshade="noshade" size="1"/><i>ab</i>&#8722;<i>r</i><sup>2</sup><br /></td><td nowrap="nowrap" align="center">
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