Question

question 9 of 10
which is the best definition of an exterior angle of a triangle?

a. an angle that forms a linear pair with one of the interior
angles of the triangle
b. an angle that is formed by two segments that are not
sides of the triangle
c. an angle that is complementary to one of the interior
angles of the triangle
d. an angle that is formed by two segments that are sides of
the triangle

Explanation:

To determine the best definition of an exterior angle of a triangle, we analyze each option:

• Option A: An exterior angle of a triangle is formed by one side of the triangle and the extension of an adjacent side. This forms a linear pair (supplementary angles) with the adjacent interior angle. This matches the definition.
• Option B: Exterior angles are formed by a side of the triangle and the extension of another side, so they involve sides of the triangle. Thus, this is incorrect.
• Option C: Exterior angles are supplementary (not complementary) to the adjacent interior angle. So this is wrong.
• Option D: Interior angles are formed by two sides of the triangle. Exterior angles involve an extension, so this describes an interior angle, not exterior.

Answer:

A. An angle that forms a linear pair with one of the interior angles of the triangle