Question

if an angle is acute, then its measure is 20°. which of the following would be a counterexample?
105°
180°
48°
90°

Explanation:

Step1: Recall definition of acute angle

An acute angle has a measure between 0° and 90°.

Step2: Analyze each option

105° is greater than 90°, so it's not acute. 180° is a straight - angle. 90° is a right - angle. 48° is between 0° and 90°, so it is an acute angle but not 20°.

Answer:

C. 48°