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Home > CC3 > Chapter 9 > Lesson 9.2.2 > Problem 9-79

9-79.

Calculate the value of . Homework Help ✎

  1. diagram a

    An exterior angle of a triangle is equal to the sum of the two remote interior angles.

  1. diagram b

    Notice that the  angle corresponds to the angle adjacent to angle . This angle is complementary to angle .

    The vertical angle is equal to the angle because they are alternate interior angles on parallel lines.