Question 850555
In an isosceles triangle, the height is a perpendicular bisector of base.
So see a right triangle with base = 3.5, and hypotenuse = 6 

{{{x^2+3.5^2=6^2}}}

{{{x^2=36-12.25}}}

{{{x^2=23.75}}}

x=4.8734 ft (not a pretty number)