1. The World Of Triangles Juliána Melicherová University of Pavol Jozef Šafárik, Košice

2. Triangles 3-sided polygon three sides and three angles together the three angles equal 180°

3. Triangle Inequality Theorem any side of a triangle is always shorter than the sum of the other two sides

4. Acute Triangles all three angles are less than 90°

5. Obtuse Triangles one of the angles is greater than 90°

6. Right Triangles with an angle of 90°

7. Scalene Triangles three unequal sides

8. Isosceles Triangles with (at least) two equal sides

9. Isosceles Triangle Theorem if two sides of a triangle are congruent, the angles opposite them are congruent

10. Equilateral Triangles with all three sides of equal length

11. Equiangular Triangles which has three equal angles

12. Congruent Triangles triangles whose corresponding angles and sides are congruent the same size and shape.

13. The Hypotenuse the triangle's longest side, i.e., the side opposite the right angle.

14. The Pythagorean Theorem for a right triangle with legs a and b and hypotenuse c, a 2 +b 2 =c 2.

15. Penrose triangle impossible object

16. Thank you for your attention!