NCERT Solution For Class 6, Maths, Chapter 4, Basic Geometrical Ideas

Key points

Point: A point determines a location and i is usually denoted by a capital letters in given figure.

Line segment: A line segment corresponds to the shortest distance between two points. The line segment joining points A and B is denoted by  $\overline{AB}$ .

Intersecting lines: Two distinct lines meeting at a point are called intersecting lines.

Parallel lines: if the two lines do not meet in a plane, they are said to be parrel lines.

Ray: it is a portion of line starting at a point and going in one direction endlessly.

Curve: Any drawing (straight or non-straight) done continuously without lifting the pencil may be called a curve.

Closed and open curve: A curve is said to be closed if its ends are joined. Otherwise, it is said to be open.

Polygon: it is a simple closed curve made up of line segments.

Triangle: A triangle is a three-sided polygon.

Quadrilateral : it is a four-sided polygon.

Circle: A circle is the path of a point moving at the same distance (the radius) from a fixed point (the centre). Here, the fixed point is the centre, the fixed distance is the radius.

Diameter: it goes straight across the circle, through the centre of circle. The diameter of a circle divides it into two semi-circles.

Circumference: the distance once around the circle is the circumference.