Question 883401
Drop a line from a vertex of one of the angles and place the other end of the line at the midpoint of the opposing side.
This height is one side of a right triangle.
The other side is (1/2)6=3 because it is the midpoint of the side.
The hypotenuse is the side of the equilateral triangle, 6.
Use the Pythagorean theorem,
{{{6^2=h^2+3^2}}}
{{{h^2=36-9}}}
{{{h=sqrt(27)}}}
{{{highlight(h=3sqrt(3))}}}
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{{{drawing(300,300,-5,5,0,10,line(-3,1,3,1),line(-3,1,0,5.196),line(0,5.196,3,1),blue(line(0,1,0,5.196)))}}},