1. Triangles… SOL5.12b GES Mrs. Norman

2. CLASSIFYING TRIANGLES

3. CLASSIFYING TRIANGLES  Why do we classify triangles?  Artists and architects often use triangular elements in their designs.  Classifying triangles makes it easier to describe them.

4. CLASSIFYING TRIANGLES  How can these triangles be classified?  One way is:  By the length of their sides. 49 8 2 7 5 5 4 4

5. CLASSIFYING TRIANGLES  Equilateral triangle  All sides are the same (equal) length.  The sum total of every triangle = 180°  So, if all of the angles are the same…  3 ÷ 180° = 60°  Each of the three angles of an equilateral triangle is 60°

6. CLASSIFYING TRIANGLES  Isosceles triangle  At least two sides are the same (equal) length. 6 4 44 4

7. CLASSIFYING TRIANGLES  Scalene triangle  No sides are the same (equal) length. 9 7 2 9 7 2

8. CLASSIFYING TRIANGLES AAnother way you can classify triangles is: bby the measure of their angles

9.  Right triangle  One angle is a right (90°) angle.  The sides have special names.  The legs are the two sides that form a right triangle  The third side is the hypotenuse legs hypotenuse

10. CLASSIFYING TRIANGLES  Acute triangle  All three angles are acute angles.

11. CLASSIFYING TRIANGLES  Obtuse triangle  One angle is an obtuse angle.

12. CLASSIFY TRIANGLES Image from math.com Isosceles: 2 congruent sides Scalene: each side a different length Equilateral: all 3 sides congruent Acute: all angles are acute Obtuse: has an obtuse angle Right: has a right angle

13. Now You know all about Triangles… So lets practice!

14. CLASSIFYING TRIANGLES BY SIDES AND ANGLES http://www.ixl.com/math/grade-4/classify-triangles-by-side-lengths http://www.ixl.com/math/grade-4/classify-triangles-by-angles http://www.ixl.com/math/grade-7/classify-triangles

15. DIRECTIONS:  When the slide appears, say BOTH NAMES for the type of triangle aloud before the computer shows you the answer.  Classify each triangle by both its SIDES and its ANGLES.  You will have 6 seconds.

16. Classify by sides: Classify by angles:

17. Classify by sides: Classify by angles: also Isosceles Triangle

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42. Are you a triangle expert?