Question

已知点A(-3,-4),B(6,3)到直线l:ax+y+1=0的距离相等,求a的值

Answer 1

| -3a - 4 + 1 | / √(a² + 1) = | 6a + 3 + 1 | / √(a² + 1)

| 3a + 3 | = | 6a + 4 |

3a + 3 = 6a + 4 或 3a + 3 + 6a + 4 = 0

a = -1/3 或 a = -7/9