x is the opposite side of the 30 degrees angle and 12 is the adjacent side. Utilizing trigonometry functions, recall that tan(angle)=opposite/adjacent. Thus, tan(30)=x/12. x=tan(30)*12
tan30=
[tex] \frac{ \sqrt{3} }{3} [/tex]
Thus x=
[tex]12 \times \frac{ \sqrt{3} }{3} [/tex]
or equivalently
[tex]4 \sqrt{3} [/tex]