If an angle measures 45°, what type of angle is it?

An angle that measures 45° is classified as an acute angle. Acute angles are defined as angles that are less than 90°, so any angle measuring between 0° and 90° falls into this category. A 45° angle fits perfectly within that range.

To provide context, right angles measure exactly 90°, obtuse angles are greater than 90° but less than 180°, and straight angles measure exactly 180°. Since 45° is less than 90°, it cannot be classified as a right angle or obtuse angle, confirming its status as an acute angle.