Answer:
Think of the altitude as a line that divides the equilateral triangle into two equal parts.
Each part is a 30, 60, 90 triangle. The altitude of the triangle corresponds to the x[tex]\sqrt{3\\}[/tex] side of the equilateral triangle.
So: 9=x[tex]\sqrt{3\\}[/tex] , and x=9/[tex]\sqrt{3\\}[/tex].
However, one side of the triangle is actually 2x, so the correct answer is
18/[tex]\sqrt{3\\}[/tex]
Let me know if this helps!
