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					   Goal – To classify
triangles according to
   angles and sides.
      Different Types of Triangles
   There are several different types of triangles.
   You can classify a triangle by its sides and its
    angles.
   There are THREE different classifications for
    triangles based on their sides.
   There are FOUR different classifications for
    triangles based on their angles.
Classifying Triangles by Their Sides
   EQUILATERAL – 3 congruent sides

   ISOSCELES – at least two sides
                                        EQUILATERAL

    congruent


                    ISOSCELES
   SCALENE – no sides congruent

                                      SCALENE
      Classifying Triangles by Their
                  Angles
   EQUIANGULAR – all angles are congruent

   ACUTE – all angles are acute
                                               EQUIANGULAR

   RIGHT – one right angle        ACUTE


                              RIGHT



   OBTUSE – one obtuse angle
                                      OBTUSE
    Can You Classify the Different
    Triangles in the Picture Below?




Classify the following triangles: AED, ABC, ACD, ACE
          The Classifications…
   Triangle AED = Equilateral, Equiangular
   Triangle ABC = Equilateral, Equiangular
   Triangle ACD = Isosceles, Obtuse
   Triangle ACE = Scalene, Right

   So how did you do?
                       Question 1
   If a triangle has three      Answer:
    unequal sides it is a            A) Scalene
    ______ triangle.
       A) Scalene
       B) Obtuse
       C) Isosceles
                         Question 2
   A triangle which has         Answer:
    three equal angles is a          C) Equiangular
    ______ triangle.
       A) Acute
       B) Equilateral
       C) Equiangular
                       Question 3
   A triangle with (at least)      Answer:
    two equal sides is a                B) Isosceles
    ______ triangle.
       A) Scalene
       B) Isosceles
       C) Congruent
                   Question 4
                                Answer:
   Two triangles that are          C) Congruent
    equal are called
    ______ triangles
       A) Acute
       B) Obtuse
       C) Congruent
                         Question 5
   A triangle with all three       Answer:
    sides of equal length is a          A) Equilateral
    ______ triangle.
       A) Equilateral
       B) Right
       C) Equiangular
                       Question 6
   A triangle with an angle      Answer:
    of 90° is a ______                B) Right
    triangle.
       A) Acute
       B) Right
       C) Congruent
                     Question 7
   A triangle in which all      Answer:
    three angles are less            B) Acute
    than 90° is a ______
    triangle.
       A) Right
       B) Acute
       C) Scalene
                       Question 8
   A triangle in which one       Answer:
    of the angles is greater          A) Obtuse
    than 90° is a ______
    triangle.
       A) Obtuse
       B) Isosceles
       C) Acute
                       Question 9
   What is the Hypotenuse            Answer:
    of a right triangle?                  B) The side opposite the
       A) The smallest angle.             right angle.
       B) The side opposite the
        right angle.
       C) The right angle.
               Word Problem 1
   In triangle ABC the measure of <B is twice the
    measure of <A, and the measure of <C is 3
    times the measure of <A. Find the number of
    degrees in each angle of the triangle.
              Word Problem 2
   The measure of each base angle of an isosceles
    triangle is 7 times the measure of the vertex
    angle. Find the measure of each angle of the
    triangle.
             World Problem 3
   In     ABC , < A = x, <B = x+45, and m<C
    = 3x-15
   Find the measures of the three angles
   What kind of triangle is ABC?
                  Writing in Math
   Taylor said that if the sum of the measures of two
    angles of a triangle is equal to the measure of the
    third angle, the triangle is a right triangle. Prove or
    disprove Taylor’s statement.
                  Homework
   Pg. 267-269 # 4-18 even, 27,29,31

				
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posted:12/3/2011
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