1. Triangles By Cody Chesney

2. Polygons Geometric Shape Closed figure Three sides

3. Angles Two types First – Interior Angles Always three Total 180°

4. Angles (cont.) Second – Exterior Angles Along line from interior angle Exterior + Interior = 180° Sum of other interior angles

5. Types of Triangles By sides: Scalene Triangles Isosceles Triangles Equilateral Triangles

6. Scalene Triangles All angles different All sides different Can be a right triangle Not always

7. Isosceles Triangles Two angles are equal Third = 180 – Sum of two equal angles Two sides are equal Third shorter than each of other two

8. Equilateral Triangles All three sides equal All three angles equal Each angle equals 60°

9. Types of Triangles (cont.) By angles: Oblique Triangles Obtuse Triangles Acute triangles Right Triangles

10. Types of Triangles (cont.) Oblique triangles Do not have a 90° angle Obtuse Triangles One angle greater than 90°

11. Acute Triangles All angles less than 90° Both Acute and Obtuse are Oblique Types of Triangles (cont.)

12. Right Triangles One angle = 90° Called “right angle” Can be isosceles and scalene Cannot be equilateral

13. Area of Triangles Area is space enclosed in figure A=(1/2)*b*h h b

14. Pythagorean Theorem Unique to right triangles Correlation between three sides a2+b2=c2

15. Pythagorean Theorem (cont.) Pythagorean triples All three sides are integers Examples: a=3, b=4, c=5 a=8, b=15, c=17

16. Citations kryptos86, “Triangles” June 6, 2010 via Flickr, Creative Commons Attribution, Noncommercial, No Derivative Works License tanakawho, “Abstract (triangle)” February 3, 2010 via Flickr, Creative Commons Attribution, Noncommercial License Swamibu, “The Great Pyramid: Size Matters” January 18, 2008 via Flickr, Creative Commons Attribution, Noncommercial License