Answer
$\text{approximately } 3.5 \text{ } in.$
Work Step by Step
Using $a^2+b^2=c^2$ (or the Pythagorean Theorem) where the legs are given the measures $2.7$ inches and $2.3$ inches, the measure of the hypotenuse, $c$, is equal to
\begin{array}{l}\require{cancel}
(2.7)^2+(2.3)^2=c^2
\\\\
7.29+5.29=c^2
\\\\
12.58=c^2
\\\\
c=\sqrt{12.58}
\\\\
c\approx3.5
.\end{array}
Hence, the unknown side is $
\text{approximately } 3.5 \text{ } in.
$
