[填空题]
Two spaceships leave Earth iddr)c+lmy8f8 qn 0n dl(ne ;z;n oppoi /*pqxe8 b3mssite directions, each with a speed of 0.50c with respect to Ee8 i3/pq xmb*sarth.
(a) What is the velocity of spaceship 1 relative to spaceship 2? u = c
(b) What is the velocity of spaceship 2 relative to spaceship 1?u = c