There is actually a cool trick to this. When you see a and 2a, in this case 6 and 12, then the small triangle is a 60-30-90 triangle. The remaining side is [tex]6 \sqrt{3} [/tex].
This value rounds down to 10, and yep, you guessed it, another 30-60-90.
This time, x = [tex]10 \sqrt{3} [/tex].
This is a very difficult problem and requires knowledge of the special triangles. Hope this helps!
