we can use pythagoras to solve the triangle

where a and b are sides and h the hypotenuse on this case we use half triangle to make a rigth triangle and apply pythagoras
a is 9, b is 20 and h the x
so replacing

solve for x
![x=\sqrt[]{9^2+20^2}](https://img.qammunity.org/2023/formulas/mathematics/college/v57s6227spoeysxqkkwe6tj9v7xx0otwjv.png)
and do the operatios
![\begin{gathered} x=\sqrt[]{81+400} \\ x=\sqrt[]{481}\approx21.93 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/u9axbf8dl5k72sf84w49dmt9rmvkpc53ed.png)
the value of x is 21.93 units