Question 878498
Start from an equilateral triangle.  The hypotenuse of the 30 60 90 triangle is one of the sides of the equilateral triangle.  If the shortest side of your 30 60 90 triangle is 6, then the hypotenuse must be {{{2*6=12}}}.  Use Pythagorean Theorem to find the length of the last side (which would be an altitude of the equilateral triangle).