A space probe is describing a circular orbit of radius nR with a speed to about a planet o...

A space probe is describing a circular orbit of radius nR with a speed to about a planet of radius R and center O. As the probe passes through point A, its speed is reduced from υ0 to βv0 where β < 1, to place the probe on a crash trajectory. Express in terms of n and β the angle AOB, where B denotes the point of impact of die probe on the planet.