program in UNIX which accepts three sides of triangle and check triangle can be formed or not.

Write a shell script which accepts three sides of triangle and check triangle can be formed or not.
echo "enter the 3 sides of da trngle"
read x y z

if [ `expr $x + $y` -gt $z -o `expr $y + $z` -gt $x -o `expr $x + $z` -gt $y ]
then
echo "The triangle can be formed "
else
echo "Triangle can not be formed!!"
fi