Consider an isosceles triangle. let

be the radius of its circumscribed circle and

be the radius of its inscribed circle. Prove that the distance

between the centers of these two circle is
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Consider an isosceles triangle. let $R$ be the radius of its circumscribed circle and $r$ be the radius of its inscribed circle. Prove that the distance $d$ between the centers of these two circle is $$d=\sqrt{R(R-2r)}$$