F = k / (r^2)
dF/dt = -2k / (r^3) dr/dt
When r = 10^4 km and dr/dt = 0.2 km/sec
dF/dt = -2(10)^3 (0.2) / ((10^4)^3) = -400 / 10^7 = -0.00004 N/s
The gravitational force is changing at the rate of -0.00004 N/s
Less than 90° = acute
more than 90° = obtuse
equal to 180° = straight
more than 360° = reflex
190 min.................................