According to the triangle inequality property, we know that the sum of two sides of a triangle is greater than the third side. Let's assume that the length of the side is x. That said, we can make the inequalities.
x + 3 > 5
8 > x
x + 5 > 3
this means that x >2, 8 > x, and x > -2. We can disregard the last inequality. We can now make an answer. We know that 2<x<8, so we can use any of those values in our answer. That makes our answer: 4 cm. and 6 cm.