Given that, The two sides of a triangle are of length 3 cm and 8 cm and the length of its third side is x cm. As we know, Sum of two sides of triagle is always greater than third side of the triangle. ∴ Sum of two sides of triagle > third side of the triangle. ⇒ 3 + 8 > Third side ⇒ 11 > x Also, Another case will be, ⇒ x + 3 > 8 ⇒ x > 8 - 3 ⇒ x > 5 ∴ 5 < x < 11