Answer:
a = 12
Step-by-step explanation:
Based on the Pythagoras theorem...
[tex]c^{2} = a^{2} + b^{2}[/tex]
(where c is the hypotenuse, and a and b are the legs of the right angle triangle)
Therefore we can rewrite it as...
[tex]c^{2} = a^{2} + b^{2}[/tex]
[tex]15^{2} = a^{2} + 9^{2}[/tex]
[tex]225 = a^{2} + 81[/tex]
[tex]a^{2} = 225 - 81\\a^{2} = 144\\a=\sqrt{144} \\a = 12[/tex]
