(i) Given 5, 7, 9
Yes, these numbers can be the lengths of the sides of a triangle because the sum of any two sides of a triangle is always greater than the third side.
Here, 5 + 7 > 9, 5 + 9 > 7, 9 + 7 > 5
(ii) Given 2, 10, 15
No, these numbers cannot be the lengths of the sides of a triangle because the sum of any two sides of a triangle is always greater than the third side, which is not true in this case.
Here, 2 + 10 < 15
(iii) Given 3, 4, 5
Yes, these numbers can be the lengths of the sides of a triangle because the sum of any two sides of triangle is always greater than the third side.
Here, 3 + 4 > 5, 3 + 5 > 4, 4 + 5 > 3