Answer
We look for the distance between the top of the building and the reference point
$tan(35^{\circ}) = \frac{x}{85} $
$x \approx 59.5176\; m$
We look for the distance between the top of the antenna and reference point
$tan(38^{\circ}) = \frac{x+h}{85} $
$x+h \approx 66.4093\;
find difference
66.4093-59.5176
$ = 6.89 m
Work Step by Step
$tan(35^{\circ}) = \frac{x}{85} $
$x \approx 59.5176\; m$
$tan(38^{\circ}) = \frac{x+h}{85} $
$x+h \approx 66.4093\; m$
$(59.5176) + h = 66.4093$
$h = 66.4093 - 59.5176 \approx 6.89 m$
