A triangle has a side length of 3/4 inches and a side length of 3 inches. What could be the length of the third side of the triangle?

we know that

The sum of the lengths of any two sides of a triangle must be greater than the length of the third side. 

therefore
(3+3/4)=3.75 in

the third side must be < 3.75 in

the length could be 3 in