Two sides of a triangle are of length 3 cm and 8 cm. If the length of the third side is 'x' cm, then:

Given,

Length of the two sides of the triangle are 3 cm and 8 cm

Length of the third side = 'x' cm

In a triangle, length of a side is less than sum of the leghth of other two sides

$$=$$>  x < 3 + 8

$$=$$>  x < 11 ......................(1)

Also, in a triangle length of a side is greater than difference of the other two sides

$$=$$>  x > 8 - 3

$$=$$>  x > 5 ........................(2)

From (1) and (2)

5 < x < 11

Hence, the correct answer is Option D