Why don’t we use a full circle as protractor?

Transcript

Why don’t we use a full circle as protractor? To measure angles, we use protractor, which is half circle We don’t use full circle, why? Let’s look at the reasons 1. Half-circle (180°) protractors are easier to use Most angles we measure in school geometry (acute, obtuse, right, straight) are less than or equal to 180°. A 180° semicircle lets you place it easily along the baseline of the angle, and read off the measurement directly. It simplifies the layout: one straight edge, center marked, and two mirrored number scales (left to right, right to left). 2. Full-circle (360°) protractors are used — but only when needed They’re used in advanced navigation, mechanical engineering, and map work. But for school-level geometry, you rarely need to measure reflex angles (>180°). So a 360° protractor is more complex than necessary. 3. Simplicity and cost Half-circle protractors are: Cheaper to manufacture Easier to store in a compass box Simple for beginners To summarise