You can put this solution on YOUR website! Length of two sides of the triangle are 3cm & 8cm.
We know that the sum of any two sides of a triangle is always greater than the third side,
So third side < 3 + 8
i.e. third side < 11
Also the difference of any two sides of a triangle is always less than the third side,
So third side > 8 - 3
i.e. third side > 5
Combining the two equations we get
11 > third-side > 5
i.e. the third side of the triangle lies between 5cm amd 11cm.