The pythagorean Theorem say:
[tex]h=\sqrt[]{l^2_1+l^2_2}[/tex]In this problem l1 and l2 will be a and b so:
[tex]h=\sqrt[]{14^2+18^2}[/tex]So finally we operate and we get:
[tex]\begin{gathered} h=\sqrt[]{196+324} \\ h=\sqrt[]{520} \\ h=22.8 \end{gathered}[/tex]