The Euler line, named after Leonhard Euler, and the nine-point circle are important in Euclidian geometry. The line passes through several important points, such as the center of the Euler circle, orthocenter, the circumcenter, and the centroid. The nine-point circle, which passes through all of the important points from the Euler line, is also significant. The properties of a triangle and its important lines are intriguing to look at. We will present several of these important features in a triangle.
