We are given the right-angle triangle with two known sides and one unknown side.
We can use the Pythagoras theorem to find the length of the unknown side.
Recall that Pythagoras theorem is given by
[tex]a^2+b^2=c^2[/tex]
Where c is the side opposite to the 90° angle.
Let us substitute the given values into the above equation
[tex]a^2+(9)^2=(15)^2[/tex]
Simplify the equation
[tex]\begin{gathered} a^2+81=225^{} \\ a^2=225-81 \\ a^2=144 \end{gathered}[/tex]
Take the square root on both sides
[tex]\begin{gathered} \sqrt[]{a^2}=\sqrt[]{144} \\ a=12 \end{gathered}[/tex]
Therefore, the length of the third side of the right angle tri
