... Pytago theorem in right triangle. Presentation and writing formulas of that theorem. Students: 2 2 2a b c if ABC is rigth triangle at A (squared length of the hypotenuse of a right triangle ... Concepts of theory of didactical situation d) Application of theory of didactical situation to teaching Thanks to researches on theory of didactical situation and application of theory of didactical ... Tien Trung (2009), Recommendation engine in teaching the cosine theorem in the triangle (Geometry for 10th grade), Journal of Educational Science, No 206, p. 35-37. 2 Nguyen Tien Trung...