Answer
$2.8\times10^5m$
Work Step by Step
As we know that:
$T^2=\frac{4\pi^2r^3}{GM}$
This can be rearranged as:
$r=\sqrt[3] {\frac{T^2GM}{4\pi^2}}$
We plug in the known values to obtain:
$r=\sqrt[3] {\frac{(112\times 60)^2(6.67\times 10^{-11})(0.642\times 10^{24})}{4\pi^2}}$
$r=3.66\times 10^6m$
We can now find the aircraft's altitude:
$ h = 3.66\times 10^6m-3.38\times10^6 m=2.8\times10^5m$
