Answer:
[tex]a = 3\sqrt{7}[/tex]
Step-by-step explanation:
Given
See attachment
Required
Determine (a)
To do this, we make use of Pythagoras theorem.
[tex]12^2 = a^2 + 9^2[/tex]
[tex]144 = a^2 + 81[/tex]
Collect like terms
[tex]a^2 = 144 -81[/tex]
[tex]a^2 = 63[/tex]
Take square roots
[tex]a = \sqrt{63}[/tex]
Expand
[tex]a = \sqrt{9*7}[/tex]
Split
[tex]a = \sqrt{9}*\sqrt{7}[/tex]
[tex]a = 3\sqrt{7}[/tex]
