Answer
137 ft
Work Step by Step
The vertical height of the tree is a leg of a right triangle, (label it with $a)$.
$a$ is opposite to the measured angle $A=70^{o}$
The other leg, ($b$=50 ft) is adjacent to A.
(SOHCAHTOA)
We use $\displaystyle \tan A=\frac{a}{b}$ and solve for $a$:
$a=b\cdot\tan A$
$ a=50\cdot\tan 70^{o}\approx$137.373870973,
which, to the nearest foot is
137 ft
