直线l的方程y - 10 = k(x - 5)
kx - y + 10 - 5k = 0
与原点的距离d = |k*0 - 0 + 10 - 5k|/√(k² + 1) = 5|k - 2|/√(k² + 1) = 5
k = 3/4
y - 10 = (3/4)(x - 5)
y = 3x/4 - 25/4