Chapter 11 Constructions

Notes

Constructions:

Drawing geometrical figures accurately Uses compass and ruler

Important instruments:

Compass Scale Pencil Protractor

Basic constructions:

Line segment Angle Triangle Circle Tangent

Important concepts:

Perpendicular bisector Divides line into equal parts Makes 90° angle Angle bisector Divides angle into two equal angles Tangent construction Tangent always perpendicular to radius

Triangle constructions:

SSS SAS ASA

Similar triangle construction:

Uses proportional division

Important points:

Keep compass radius fixed carefully Draw neat diagrams Use sharp pencil

Common mistakes:

Wrong compass opening Improper measurements Untidy arcs Wrong angle marking