The distance from the focus to the collimator is 5, and the parabolic standard equation is solved RT.

The distance from the focus to the collimator is 5, and the parabolic standard equation is solved RT.

The distance from focus to guide line = P / 2 + P / 2 = P = 5.2p = 10
There may be four parabolic equations: x ^ 2 = 10Y, x ^ 2 = - 10Y; y ^ 2 = 10x, y ^ 2 = - 10x