Question

Which of the following could NOT be the lengths of the sides of a triangle?

Answer 1

Given:

Sides of triangles in the options.

To find:

Which could NOT be the lengths of the sides of a triangle.

Solution:

Condition for triangle:

Sum of two smaller sides of a triangle must be greater than the longest side.

In option A,

$5+5=10>5$

Sides 5 in, 5 in, 5 in are the lengths of the sides of a triangle.

In option B,

$10+15=25>20$

Sides 10 cm, 15 cm, 20 cm are the lengths of the sides of a triangle.

In option C,

$3+4=7>5$

Sides 3 in, 4 in, 5 in are the lengths of the sides of a triangle.

In option D,

$8+5=13$

Since, the sum of two smaller sides is less than the longest side, therefore the sides 8 ft, 15 ft, 5 ft are not the lengths of the sides of a triangle.

Therefore, the correct option is D.