Question 870883
Think of the triangle as two right triangles put together back to back -- each of those triangles would have a hypotenuse of 6 and a base of 3.  You're looking for the third leg.
{{{3^2 + x^2 = 6^2}}}
9 + {{{x^2}}} = 36
Subtract 9 from each side
{{{x^2}}}=25
sq rt each side
x = 5
.
The height is 5.