6. The "Shenzhou 5" spacecraft launched by our country began to operate on an elliptical orbit with the Earth's center $F$ as one of its foci. It was measured that the perigee $A$ is 200 kilometers above the ground, and the apogee $B$ is 350 kilometers above the ground. The radius of the Earth is 6371 kilometers. Therefore, the maximum angle of view of the Earth from a point on the elliptical orbit is
A. $2 \arcsin \frac{6371}{6571}$
B. $2 \arcsin \frac{6371}{6721}$
C. $2 \arccos \frac{6371}{6721}$
D. $2 \arctan \frac{6371}{6571}$
6. A Prompt: It is evident that the angle between the two tangents drawn from the perigee $A$ to the Earth's surface corresponds to the maximum viewing angle.



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