An obtuse triangle is formed if there is an angle that has a measure of more than 90 degrees. You can determine if an obtuse angle is formed by two sides of a triangle if it meet this condition:
Let a and b be two sides of a triangle and c is the longest side:
So taking your given:
< 
100 + 225 <
325 <
To get the smallest possible number, just get the square root of both sides:
< 
18.03 < c
So your smallest possible whole number is 19
Let a and b be two sides of a triangle and c is the longest side:
So taking your given:
100 + 225 <
325 <
To get the smallest possible number, just get the square root of both sides:
18.03 < c
So your smallest possible whole number is 19