Answer
$h = 1103.6~mi$
Work Step by Step
$h = R~(\frac{1}{cos~\frac{180~T}{P}}-1)$
We can find $h$ when $T = 30~min$ and $P = 140~min$:
$h = R~(\frac{1}{cos~\frac{180~T}{P}}-1)$
$h = (3955~mi)~\left[\frac{1}{cos~\frac{(180)(30~min)}{140~min}}-1\right]$
$h = (3955~mi)~\left[\frac{1}{cos~38.57^{\circ}}-1\right]$
$h = 1103.6~mi$
