E
eclipsis


1/ [TEX]\sqrt{x^2 -3ax+a^2} + \sqrt{x^2 +3ax+a^2} =2a[/TEX]
2/ [TEX](a+b)\sqrt{a^2 +b^2 +x^2}-(a-b)\sqrt{a^2 +b^2 -x^2}=a^2 +b^2[/TEX]
3/ [TEX]x^2 =\sqrt{a-x}+a[/TEX]
2/ [TEX](a+b)\sqrt{a^2 +b^2 +x^2}-(a-b)\sqrt{a^2 +b^2 -x^2}=a^2 +b^2[/TEX]
3/ [TEX]x^2 =\sqrt{a-x}+a[/TEX]