Question

Triangle ABC is reflected over the x-axis. Triangle ABC has points A (10, 2), B (9,5), and C

(6,4). What is the B' coordinate?

Answer 1

A reflection over a line l moves every point P of the plane to the point P ′ on the perpendicular from P to the line l and on the same distance from l .

If the line is the x -axis, a point P = ( p 1 p 2 ) moves to the point P ′ = ( p 1 , − p 2 ) .

The image of the triangle A B C is the triangle A ′ B ′ C ′ with B ′ = ( 9 , − 5 )