The three sides of a triangle are a, b, and c. It is known that a**2=424, b**2=98, c**2=130. Find the area of this triangle.
一个三角形的三条边分别是a、b、c，已知a**2=424，b**2=98，c**2=130．求这个三角形的面积．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 16 * 7</gadget>
<output>28</output>

<result>28</result>