can you help me know how to get the answer i don’t need the answers just how to solve the problem

Answer:
I guess 21
Step-by-step explanation:
Because if you find the other side by trigonometric theorem-
[tex]x^2 = c^2 - a^2\\x^2 = 12^2 -8^2\\x^2= 144 - 64\\x^2=80\\\sqrt{x} =\sqrt{80}\\ x=8.94[/tex]
which is almost 9
9 is a possible value
they ask you to find the value which doesn't fit in the triangle
so the answer is 21 which doesn't make any sence
Hopefully, the answer would be work