Contact Triangle

The contact triangle of a triangle , also called the intouch triangle, is the triangle formed by the points of tangency of the incircle of with .

Adams' Circle

Given a triangle , construct the contact triangle . Now extend lines parallel to the sides of the contact triangle from the Gergonne point. These intersect the triangle in the six points , , , , , and . C. Adams proved in 1843 that these points are concyclic in a circle now known as the Adams' circle.

Circle

A circle is the set of points in a plane that are equidistant from a given point . The distance from the center is called the radius, and the point is called the center. Twice the radius is known as the diameter . The angle a circle subtends from its center is a full angle, equal to or radians.

In planimetry theorem, in stereometry unsolved problem

U planimetriji teorem, u stereometriji nerijeseni problem

Incircles in a quadrilateral and its subtriangles

Кружници во четириаголник и негови субтриаголници

Теорема на Vivianli

Vivianli's theorem

О НЕКИМ ИНТЕРЕСАНТНИМ ПРИМЕНАМА НЕЈЕДНАКОСТИ ТРОУГЛА

Srediste trokutu upisane kruznice i Eulerov pravac

Similar Triangles Problems - Solutions

Similar Triangles - Problems

Similar Triangles Examples

Definition

Two triangles ABC and A'B'C' are similar if the three angles of the first triangle are congruent to the corresponding three angles of the second triangle and the lengths of their corresponding sides are proportional as follows.

Similar Triangles Problems with Solutions