The lengths of three line segments (in cm) are given in each of the four cases. Which one of the following cases is not suitable to be the three sides of a triangle?

• A. 2, 4, 5
• B. 2, 3, 4
• C. 3, 4, 5
• D. 2, 3, 5

Answer: (D)

We know that in any triangle "the sum of two sides is always greater than its third side" and "the difference of two sides is always less than its third side".(i) 2 + 3 is not greater than 5 (ii) |5 - 2| not less than 3