Let the unknown side be h
Pythagoras theorem states that the square of the hypotenuse is equal to the square of the opposite plus the square of the adjacent in any right angled triangle
[tex]\begin{gathered} \text{From the figure, } \\ \text{hypotenus = h} \\ \text{Let opposite = 3, adjacent = 10} \\ \text{Therefore, applying pythagoras theorem,} \\ h^2=3^2+10^2 \\ h^2=9+100 \\ h^2=109 \\ h=\sqrt[]{109} \\ h=10.44 \\ h\approx10.4\text{ (nearest tenth)} \end{gathered}[/tex]
The missing length is 10.4
