Mathematics for IGCSE & O level - Geometrical Constructions (Section 2 - No. 30)
What is the first step in measuring an angle?
Align the zero line of the protractor with one arm of the angle.
Estimate the angle size.
Look for the correct scale on the protractor.
Read the scale directly from the protractor.
Explication
The first step is always to estimate the angle's size.