Identifying Triangles

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Identifying Triangles

• Mr. Hayes
• Geometry

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Indiana Academic Standard G.4.1

• G.4.1 Identify and describe triangles that are
  right, acute, obtuse, scalene, isosceles,
  equilateral, and equiangular.

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Types of Triangles

• Right
• Acute
• Obtuse
• Equiangular

• Scalene
• Isosceles
• Equilateral

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Properties of Triangles

• Every triangle must have 3 sides.
• 2 legs and a base.
• Each side has a corresponding angle.
• The sums of the angles MUST equal 180 degrees.

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Right Triangle

• Right Triangles are determined by observing the
  angle measures.
• One of the angles has a measurement of 90
  degrees.
• The sum of the two remaining angles is 90
  degrees.

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Acute

• Acute angles are determined by observing angular
  measurement.
• All angles are smaller than 90 degrees.
• An acute triangle can also be isosceles,
  equiangular, or scalene.

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Obtuse

• Obtuse triangles are determined by angle
  measurement.
• One of the angles must be greater than 90
  degrees.
• The side corresponding to this angle is the
  hypotenuse.
• An obtuse triangle can be a scalene or isosceles
  triangle.

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Equiangular

• Equiangular triangles are determined by angle
  measurement.
• Each angle has the same measurement.
• All three interior angles are 60 degrees.

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Scalene

• Scalene triangles are determined by the length of
  each side.
• Each side of a scalene triangle is different from
  the other.
• Scalene triangles can be obtuse or acute.

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Isosceles

• Isosceles triangles are determined by the length
  of each side.
• An isosceles triangle has two sides that are the
  same length.
• The corresponding angles are the same.
• The two angles have the same measurement.

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Equilateral

• Equilateral triangles are determined by the
  length of each side.
• Each side has the same length.
• An equilateral is always equiangular.

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Diagrams
Equilateral / Equiangular
Obtuse
Acute
Right
Isosceles
Scalene
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Review

• What kind of triangles can have 2 sides of the
  same length?
• What is the distinct characteristic about a right
  triangle?
• What is an acute triangle?
• What triangle has an angle larger than 90
  degrees?
• Which triangle has 3 sides or 3 angles that are
  the same?

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Citations

• http//www.aaamath.com/geo318-triangle-angles.html
  
• http//www.icteachers.co.uk/children/sats/triangle
  s.htm

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The End