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Home > INT1 > Chapter 8 > Lesson 8.2.2 > Problem 8-113

8-113.

Use the angle relationships in the diagram below to determine the value of each variable. Name which geometric relationships you used.

Since the highlighted angles are vertical angles, and vertical angles are equal,
.

is an alternate interior angle to . Recall that alternate interior angles are equal.

Use the Triangle Angle Sum Theorem to calculate .

To find , notice that it is the exterior angle in the small triangle that contains and . What relationship do those angles have?