The question is on the attached sheet.
Without loss of generality, let's assume that A is directed along the positive X axis and that B is directed along the positive Y axis.
So the vectors for the velocity of a and b, in the frame of reference where is 0 is the origin of the frame,
Vao = (va, 0) and Vbo = (0, vb), where the o indicates the frame of reference where the ...
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