Question

What is the distance between point (5, 9) and its reflection across the y-axis?

Answer 1

10 units

Explanation:

Given: Point is
`(5,9)`

To find: the distance between point
`(5,9)` and its reflection across the y-axis

Solution:

Reflection of point
`(x,y)` is
`(-x,y)` across the y-axis

So, reflection of point
`(5,9)` is
`(-5,9)` across the y-axis

Distance between points
`(x_1,y_1),(x_2,y_2)` is given by
`√((x_2-x_1)^2+(y_2-y_1)^2)`

Let
`(x_1,y_1)=(5,9),(x_2,y_2)=(-5,9)`

So,

the distance between point (5, 9) and its reflection across the y-axis =
`√((-5-5)^2+(9-9)^2)=√(100)=10`

Distance = 10 units