Triangle ABC is an equilateral triangle with side lengths of 10 inches.What is the length, in INCHES, of AD?

The height of an equilateral triangle is found by the formula:
height = (sq root (3) / 2 ) * side length
height = ( 1.7320508076  / 2) * 10
height = (  0.8660254038 ) * 10
height = 8.660254038 inches