[tex]a,b,c- sides\ of \ triangle\\\\Conditions\ for\ triangle \existing\\\\a+b>c\\b+c>a\\a+c>b\\\\\ a=7\\b=12\\\\1.\\7+12>c\ \ \ -->c<19\\2.\\12+c>7\ \ \ -->c>7-12\ \ c>\ -->-5\\3.\\7+c>12\ \ -->c>12-7\ \ -->c>5\\\\Product \ of\ all\ conditions\\ c\in(5,19)[/tex]