Question

If point `P(3,10)` is reflected across the line `y=1`, what are the coordinates of its reflection image?

Answer 1

`P'=(3,-8)`

Explanation:

`" the line "y=1" is a horizontal line passing through all"`
`"points with a y-coordinate of 1"`

`"the point "(3,10)" reflected in this line"`

`"the x-coordinate remains in the same position"`

`"but the y-distance "=10-1=9`

`"under reflection the y-coordinate will be 9 units"`
`"below the line "y=1`

`"that is "1-9=-8`

`rArrP(3,10)toP'(3,-8)`
graph{(y-0.001x-1)((x-3)^2+(y+8)^2-0.06)((x-3)^2+(y-10)^2-0.06)=0 [-20, 20, -10, 10]}