Answer:
Rt≅6377Km
Explanation:
Take a look at the image. The horizontal line is the horizon, and the angle α corresponds to the earth rotation during the 77 seconds.
With this information, we can know the value of α:
α = [tex]\alpha= \frac{77s}{1day}*\frac{1day}{24H}*\frac{1H}{60min}*\frac{1min}{60s}*2*\pi =0.0056rad[/tex]
Since we have formed a rectangle triangle:
[tex]cos\alpha =\frac{Rt}{Rt+100m}[/tex] Solving for Rt:
Rt≅6377467m=6377Km