1. What is an interior angle of a triangle?
A. an angle created when the sides of the triangle are extended
B. an acute angle
C. an angle inside the triangle
D. an obtuse angle
2. True or false: Exterior angles are the angles created when the sides of the triangle are shortened.
A. This statement is true.
B. This statement is false. Exterior angles are pairs of angles whose measures add up to 360°
C. This statement is false. Exterior angles are the angles created when the sides of the triangle are extended.
D. This statement is false. Exterior angles are the angles inside the triangle.
3. Which theorem is used to prove the Triangle Angle Sum Theorem?
A. No theorems are used in this proof.
B. The Alternate Interior Angles Theorem is used.
C. The Alternate Exterior Angles Theorem is used.
D. The Triangle Angle Sum Theorem is used.
4. Suppose two statements in a proof of the Triangle Angle Sum Theorem are m∠a+m∠X+m∠b=180° and ∠a≅∠W, ∠b≅∠Y. What would the justification be for concluding m∠W+m∠X+m∠Y=180°?
A. Substitution Property of Equality
B. Transitive Property of Equality
C. Distributive Property
D. Addition Property of Equality
5. What is the missing reason in the partially completed two-column proof below?
Given: Triangle DEF Prove: The measures of the interior angles sum to 180°.
A. Same-Side Interior Angles Theorem
B. Alternate Interior Angles Theorem
C. Corresponding Angles Postulate
D. Alternate Exterior Angles Theorem