Here, we want to get the length of the ladder
The kind of triangle we have is a right triangle for which obeys the Pythagoras' theorem
According to the theorem, the square of the hypotenuse equals the sum of the squares of the two other sides
The length of the ladder marked as h is the hypotenuse
Thus, we have it that;
[tex]\begin{gathered} h^2=9^2+7^2 \\ h^2\text{ = 81 + 49} \\ h^2\text{ = 130} \\ h\text{ = }\sqrt[]{130} \\ h\text{ = 11.40 meters} \end{gathered}[/tex]