An acute angle is less than 90°. An obtuse angle is between 90° and 180°. A reflex angle is between 180° and 360°. The size of an angle can be estimated without using a protractor.

It might be useful to look at M1 Properties of Angles and M1 Properties of 2D shapes. Constructions are accurate drawings of shapes using a ruler and protractor. From a sketch or a description ...