can 19cm,9cm,11cm construct a triangle

yes, because 19<9+11

On a triangle, the longest side cannot be longer than the sum of the other two sides.

To determine if the lengths 19cm, 9cm, and 11cm can construct a triangle, we need to apply the triangle inequality theorem. According to this theorem, in a triangle, the sum of the lengths of any two sides must be greater than the length of the third side.

In this case, let's check if this condition holds for each combination of sides:

1. 19cm + 9cm > 11cm: Yes, 28cm > 11cm.
2. 19cm + 11cm > 9cm: Yes, 30cm > 9cm.
3. 9cm + 11cm > 19cm: Yes, 20cm > 19cm.

Since all three combinations satisfy the triangle inequality theorem, we can conclude that a triangle can be constructed using the lengths of 19cm, 9cm, and 11cm.