Answer:
72 units
Explanation:
The Pythagorean Theorem states that
in a right triangle when a and b are the two legs and c is the hypotenuse (the longest side).
In the diagram, 30 measures one of the legs and 78 measures the hypotenuse. Plug these in as a and c.
![30^2+b^2=78^2\\900+b^2=6084](https://img.qammunity.org/2022/formulas/mathematics/high-school/om9ll4kws7yp9ymdxe0y90zsg22890sl8k.png)
Subtract 900 from both sides
![900+b^2-900=6084-900\\b^2=5184](https://img.qammunity.org/2022/formulas/mathematics/high-school/naszj0jn3g7408x8k0hzv48k1r98gcc5ru.png)
Take the square root of both sides
![900+b^2-900=6084-900\\√(b^2) =√(5184)\\b=72](https://img.qammunity.org/2022/formulas/mathematics/high-school/x6jzq5y5o6mt51nyppo12q4uddmrsp56mf.png)
Therefore, the length of the missing side is 72 units.
I hope this helps!