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source: ncert
topic: geometry
class_level: class_7
chapter: ch10
difficulty: beginner
---
Class 7 | Ch10: Practical Geometry
Five triangle construction cases: SSS, SAS, ASA, RHS, AAS.
SSS: draw base, arc from both ends, intersection=third vertex.
SAS: draw base, angle at one end, mark distance on angle ray, join.
ASA: draw base (included side), angles at both ends, intersection=third vertex.
RHS: right angle, hypotenuse from far end, intersection=right angle vertex.
AAS: find third angle (180-sum of two given), then use ASA method.
Parallel lines: draw transversal, copy angle at new point.
SAS example: PQ=5cm, QR=4.5cm, angle Q=60°. Draw QR=4.5. Angle 60° at Q. Mark P at 5cm. Join PR.
SSS example: sides 5,6,7. Draw base 6. Arc radius 5 from one end. Arc radius 7 from other. Intersection=third vertex.
Check triangle inequality before constructing. Use sharp pencil. |