Question

一个高中必修2的直线方程题点P（-3,4）关于直线4x-y-1=0的对称点的坐标是什么?另外,哪个大侠能告诉我做直线方程

Answer 1

4x - y -1 = 0

y = 4x - 1, 斜率4

设对称点为P'(p, q),PP'与直线交于A

PP'斜率 -1/4, 方程: y -4 = (-1/4)(x +3)

与y = 4x - 1联立得A(1, 3)

A为PP'中点: 1 = (-3 + p)/2, p = 5

3 = (4 + q)/2, q = 2

P'(5, 2)