Answer:
A set of all positive integers between 7 and 43.
Step-by-step explanation:
If a triangle is given with the sides a, b, c, triangle is possible when,
a + b > c
a + c > b
b + c > a
Following the same rule in a triangle having side lengths 18, 25 and l unit.
18 + 25 > l ⇒ l < 43
18 + l > 25 ⇒ l > 7
25 + l > 18 ⇒ l > -7
Therefore, length of the third side of the triangle will be,
7 < l < 43 (A set of positive integers between 7 and 43)
