$\"\"$

The angle of triangle $\"\"$ and its side is $\"\"$ .

If sketch the none triangles then necessary condition: $\"\"$ is acute, $\"\"$ .

$\"\"$ (Write condition)

$\"\"$ (Substitute $\"\"$ )

$\"\"$ (Divide each term by $\"\"$ )

$\"\"$ (Rewrite form) $\"\"$

The solution is $\"\"$ .