答案应有两个:3/5i+4/5j或 -3/5i-4/5j 过程如下:设与向量a垂直的单位向量b = (x, y)则a • b = 0 ~ (1) ∣b∣ = 1 ~ (2)(1): (4, -3) • (x, y) = 0 4x - 3y = 0 ~ (3)(2): √(x² + y²...