What is a triangle?

3. What is a triangle? A closed in shape with three sides.

4. How are triangles classified? side angle Triangles are classified by the length of their sides or angles.

5. Equilateral What word to you notice in that? EQUAL - means the SAME All sides are the same length. All angles equal 60 degrees.

6. If an equilateral triangle has three angles 
that equal 60 degrees, what is the sum? 60 x 3 =180 degrees If all triangles have three sides and 
three angles, what will be the sum of 
all the angles? 180 degrees - no matter what type of triangle you have!

7. Isosceles At least two sides and two 
angles are the same.

8. Scalene Has no equal sides or angles.

9. Can an scalene triangle be an 
equilateral triangle? No, an equilateral triangle has three equal sides. Can a scalene triangle be an 
isosceles triangle? No, an isosceles triangle has to have at least two equal sides.

10. Define these triangles by their sides. Pull the star out to reveal a 
problem. Decide what type of triangle. Pull star to blue box to check. Push star to trash can. Repeat until there are no more 
problems to reveal. 8 mm Pull Pull 6 yd 6 yd 9 cm 9 cm 4 in 4 in 7 cm 7 cm 5 mm 6 m 5 m 6 mm 9 yd isosceles scalene 9 cm 4 in Triangle 3 cm 3 m scalene isosceles equilateral equilateral

11. After you identify an angle by its sides, you 
can identify it by its angles. What are these angles? acute right obtuse drag the dart to the target to check answers

12. Right Has one right angle (90 degrees).

13. Can a right triangle be an equilateral triangle? No, an equilateral triangle only has 60 degree angles. Can a right triangle be an isosceles triangle? Yes, it can still have two equal sides. Can a right triangle be a scalene triangle? Yes, it could have three different lengths of sides.

14. Acute All angles are acute (less than 90 degrees).

15. Can an acute triangle be an equilateral triangle? Yes, all of the angles are acute. Can an acute triangle be an isosceles triangle? Yes, it can still have two equal sides. Can an acute triangle be a scalene triangle? Yes, it could have three different lengths of sides.

16. Obtuse Has one obtuse angle (greater than 90 degrees). Can a triangle have more than 
one obtuse angle? No, an obtuse angle is 90 degrees. If 
it had 2 obtuse angles it would be 
greater than 180 degrees.

17. Can an obtuse triangle be an equilateral triangle? No, an equilateral triangle has all acute angles. Can an obtuse triangle be an isosceles triangle? Yes, it can still have two equal sides. Can an obtuse triangle be a scalene triangle? Yes, it could have three different lengths of sides.

18. Match the word and the definition.

19. What kind of triangle is it?

20. http://studyjams.scholastic.com/studyjams/jams/math/geometry/classify-triangles.htmhttp://studyjams.scholastic.com/studyjams/jams/math/geometry/classify-triangles.htm

21. Angles in a triangle Drag out the angle segments o The sum of the measure of the angles in a triangle is 180o

22. Find the measure of the angles

23. all acute 1 right 1 obtuse 0 at least 2 3

25. 9-4 Grade: «grade» «subject» Subject: «date» Date:

26. 1 A B C

27. 2 A B C

28. 3 A B C

29. 4

30. 5 A B C