Mathematics · Class 6
Basic Geometrical Ideas
Points, lines, rays, curves, polygons, and angles — foundation of geometry.
4 sections15–25 min read6 MCQs · 2 examples
Chapter Overview
Geometry begins with points, lines, curves, polygons, and angles. You learn vocabulary — segment, ray, parallel, intersecting — and how to name and classify basic figures.
Points, Lines, and Curves
- Point: exact location, no size (denoted by capital letter)
- Line segment: part of line with two endpoints
- Ray: has one endpoint, extends infinitely in one direction
- Line: extends infinitely in both directions
Angles and Polygons
- Angle: formed by two rays with common vertex
- Types: acute (<90°), right (=90°), obtuse (>90°), straight (=180°)
- Triangle: 3 sides; quadrilateral: 4 sides
- Circle: all points equidistant from centre
Parallel and Intersecting Lines
Parallel lines never meet. Intersecting lines cross at one point. Perpendicular lines intersect at 90°. These ideas appear in maps, buildings, and design.
Solved Examples
Step-by-step solutions — read each step before checking the final answer.
Example 1: Naming an Angle
Name the angle formed by rays OA and OB with vertex O.
- 1Vertex is the middle letter
- 2Use ∠AOB or ∠BOA
Answer
∠AOB
Example 2: Classify Angle
An angle measures 125°. Classify it.
- 1125° > 90° and < 180°
Answer
Obtuse angle
Key Points to Remember
- ✓ Use correct notation: line AB, segment AB, ray AB→
- ✓ Diameter is longest chord of a circle
- ✓ Diagonals join non-adjacent vertices of a polygon
Exam Tips
- • Label diagrams clearly in geometry answers
- • State angle type with reason (compare to 90°)
Practice MCQs — Basic Geometrical Ideas
Test your understanding with topic-wise multiple choice questions. Explanations appear after each answer.
Question 1 of 6Score: 0/0
A line segment has: