2r*s = 58 * 2 = 116\\&amp;#10;r^{2} + s^{2} + 2rs = 208 + 116 = 324\\&amp;#10;(r+s)^{2} = 324\\&amp;#10; \sqrt{(r+s)^{2} } =  \sqrt{324}   &amp;#10;\\ r+s = 18&amp;#10;&amp;#10;