1. If isosceles ΔABC has its vertex angle at ∠C, then

            A)                B)                 C)                 D) ∠C ≅ ∠B


2. ΔABC has m∠C = 42° and m∠A = 80°, then the correct classification for the triangle is:

            A) Acute                      B) Right                       C) Obtuse                    D) Isosceles


3.is the mid-segment of ΔABC.  Which of the following is a false statement?           


            A) DE = 2BC                 B) AD = EC                   C) 2DE = BC                 D) ∠B ≅ ∠C


4. is the mid-segment of ΔABC and m∠A = 90°.  If AD = 3 cm and AE = 4 cm, then:


            A) BC = 14 cm                                                 B) BC = 10 cm


            C) BC = 8 cm                                                   D) BC = 6 cm
5. ΔABC has m∠A = 44° and m∠C = 46°, then the triangle is a right triangle.                                    T    or    F
6. If a base angle of an isosceles is 70°, then the vertex angle is acute.                                                  T    or    F
7. If isosceles ΔABC has a vertex angle, ∠B,  of 83°, then m∠A = 49°                                                 T    or    F

8. Jennifer has seen an informal proof that the three angles of a triangle sum to 180°.  She draws a triangle on a piece of paper and then cuts it out.  She then tears off the three corners (angles) of the triangle.  What does she do next?  How does this help to support that the sum of a triangle is 180°?


She would place the three angles together so that the vertices all touch and they adjacent.  When this happens the three angles form a straight line.  A straight angle is equal to 180°… thus the sum of the angles is 180°.


9. Determine the value(s) of the variables.


Answers:          a) x = 55.5                     b) x = 12                                              c) x = 106.5


10. Prove that the sum of the interior angles of a triangle is 180° using a transformational approach.


    Questions developed for Objective G.CO.10

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