Question 1. Determine whether the biconditional statement is true or false. If false, give a counterexample.

An angle is a straight angle if and only if it is not acute.


A. false; m∠1 = 180°, ∠1 is not an acute angle
B. true
C. false; m∠1 = 63°, ∠1 is not a straight angle
D. false; m∠1 = 102°, ∠1 is not a straight angle

Question 2. Determine whether the biconditional statement is true or false. If false, give a counterexample.

An angle is a right angle if and only if it is not obtuse.


1. false; m∠1 = 70°, ∠1 is not a right angle
2. false; m∠1 = 90°, ∠1 is not an obtuse angle
3. true
4. false; m∠1 = 120°, ∠1 is not a right angle