we know that
in the right triangle ABC (see the attached figure with letters to better understand the problem)
[tex] AB=8\ cm \\\\ BC=\frac{9.4}{2}=4.7\ cm [/tex]
Applying the Pythagorean Theorem
[tex] AB^{2} =BC^{2}+AC^{2}\\ AC^{2}=AB^{2}-BC^{2}\\ AC^{2}=8^{2}-4.7^{2}\\ AC^{2}=41.91\\ AC=6.47\ cm [/tex]
[tex] AC=6.5\ cm [/tex]
therefore
the answer is
the length of the apothem is equal to [tex] 6.5\ cm [/tex]
