Q1
What formula finds a regular polygon's central angle?
A360°/n
B180°/n
C90°/n
Dn/360°
ICSEClass 9 (ICSE)MathematicsCh 15 · Topic 2
Practice and Revision - Construction of Polygons
Let us practise and revise what we learned about construction of polygons. Constructing polygons accurately requires using given measurement
Core concept
To construct a regular polygon, we can use the central angle formula (360°/n) to divide a circle into equal parts, connecting the points.
How it works
For irregular polygons, we typically need enough given measurements (like sides and angles) to uniquely determine the shape.
Why it matters
We use a ruler for accurate lines, a protractor for measuring angles, and a compass for arcs and equal distances.
Key detail
Practising polygon construction builds precision and understanding of geometric relationships between angles and sides.
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Quick notes
• Regular polygons use central angle 360°/n.
• This divides a circle into equal parts.
• Points are connected to form the polygon.
• Irregular polygons need enough given measurements.
• A ruler draws accurate lines.
• A protractor measures angles.
• A compass draws arcs and equal distances.
• Practice builds precision and geometric understanding.