Answer:
10.4 cm. to the nearest tenth.
Explanation:
The line from the vertex to the midpoint of the base is the height.
This forms a right triangle with angles 30-60 -90 so the sides are in the ratio
2x : x : √3x where 2x is the hypotenuse ( the side of the equilateral triangle) and √3x is the height.
So 2x = 12
x = 6
and √3x = 6√3 cm.
= 10.4 cm.