mathinschool.com
numbers and algebraic expressions
logic, sets, intervals
absolute value
function and its properties
linear function
quadratic function
polynomials
rational function
exponential function
logarithm
number sequences
limits of sequences and functions
derivative and integral of functions
trigonometry
plane geometry
analytic geometry
solid geometry
combinatorics
probability
elements of statistics
kropki game

On the circle mark any point A. Draw the lines at right angle to the line k and pass through points A and center of a circle. Find with compass point A' at the same distance from line k as the point A. In the same way find point O'. Draw the circle with center O' and passes through the point A'. Get the image of the circle under reflection over the line k.