we know that
The triangular inequality establishes that:
The sum of the lengths of any two sides of a triangle is greater than the third
side
therefore
if
a=3/4 in----> 0.75 in
b=3 in
c= third side of triangle
(a+b) > c
(3+0.75) > c
3.75 > c--------> c < 3.75 in
so
the answer is
the length in inches of the third side of the triangle must be minor a 3.75 in