Class 6 · Chapter 4
Basic Geometrical Ideas
Points, lines, line segments, rays, angles, triangles, polygons and circles.
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Detailed theory
Point: has position, no size. Line: extends infinitely both ways. Line segment: portion of a line with two endpoints. Ray: starts at one point, extends in one direction.
Key concepts & formulas
01
A line has no end points; a segment has two; a ray has one.
02
An angle is formed by two rays with a common vertex.
03
A polygon is a simple closed figure made of line segments.
04
The number of diagonals in an -gon is .
05
A circle is the set of points equidistant from a fixed centre.