This document discusses the key attributes of triangles. It defines triangles as shapes that have 3 sides, 3 angles, and 3 vertices. It describes the different types of triangles based on their angles (acute, obtuse, right, equiangular) and sides (isosceles, equilateral, scalene). The document also covers triangle properties like angle sum, relationships between sides and angles, calculating area, and the use of triangles in 3D shapes.

2. ▲ 3 sided
▲ 3 line segments
▲ 3 angles
▲ 3 vertices
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3. ▲ 2 acute angles
▲ Convex shape
▲ No sides parallel
▲ Not a quadrilateral
▲ Is a polygon
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http://www.geom.uiuc.edu/~wanous/definitionofatriangle.html

4. ▲ Obtuse
▲ Right
▲ Acute
▲ Equiangular
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http://studybasicmaths.blogspot.com/2010_08_01_archive.html

5. BY SIDES
▲ Isosceles
▲ Equilateral
▲ Scalene
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http://www.education.com/study-help/article/types-triangles/

6. ▲ Sum of all sides
▲ Pythagorean Theorem
http://www.mathsteacher.com.au/year7/ch12_length/07_triangle/triangle.htm
http://www.samosguide.com/listingview.php?listingID=44 6

7. ▲ ½ base x height
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8. ▲ Sum = 180°
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http://www.wyzant.com/Help/Math/Geometry/Triangles/Angles_of_Triangles.aspx

9. AT T R I B U T E S O F A N Y AT T R I B U T E S O F S O M E
RIGHT TRIANGLE RIGHT TRIANGLES
▲ 1 right angle ▲ May have 2
▲ 2 acute angles congruent angles
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http://mathworld.wolfram.com/RightTriangle.html

10. ▲ Pyramids
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http://www.mathsisfun.com/geometry/pyramids.html

11. ▲ Tetrahedron
▲ Octahedron
▲ Icosahedron
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http://www.math.rutgers.edu/~erowland/polyhedra.html