Solution
For this case we can name the lenghts like this:
a= 3
b= 13
c= 15
We need to satisfy that :
a+b >c
b+c > a
c+a > b
And we can verify that:
3+13 > 15
13+ 15 > 3
15+ 3 > 13
So therefore this triangle can exists
Since we dont satisfy the Pythegoras theorem given by.
Then this triangle is not a right triangle
And since:
c^2 > 13^2 +3^2
15^2 > 169 +9
225 > 169+9
Then the triangle needs to be obtuse