Reflection over the line y=x is a geometric transformation that maps every point of an object to a new position with the line y=x acting as a mirror.
The distance from the original point to the mirror line is equal to the distance from the image point to the mirror line, and the line connecting the original point to its image will be perpendicular to the line .
If a line has the equation y=2x+3 is reflected over the line y=x, determine the equation of its image.
To find the equation of the image, we use the rule x′=y and y′=x. This means we replace every x in the original equation with y (or y′) and every y with x (or x′).
Original equation:
y=2x+3
Substitute x→y and y→x (using x and y for the new variables for simplicity):
x=2y+3
This is the equation of the image line. Usually, we rewrite this equation in the form y as a function of x:
x−3=2y
y=21x−23
So, the equation of the image of the line y=2x+3 after reflection over y=x is y=21x−23.