A point(dot) is a small mark that has position,but no magnitude. A dot has neither shape nor size. It is represented by a small dot and denoted by a capital letter like dot 'P', dot 'Q' and dot 'R' as shown here.
The tip of a nail or pin can be taken as a physical model of a dot. In reality,a dot in geometry is even smaller than the tip of a nail or pin.
There are two types of dots 1) Collinear 2) non-collinear.
1) Collinear : If three or more dots on the same plane lie on the same line, they are known as collinear .
Dots A, B,C and D which lie on line l are collinear . Line l is known as the Line of collinearity.
2) Non-collinear : If three or more dots on the same plane do not lie on the same line, they are known as non- collinear.
The dots P,Q and R are non-collinear .
Q.1 State whether the following statements are true or false.
i) A dot has no length and no width.
ii) A dot has thickness.
iii) An infinite number of dots lie on a circle.
iv) Non-collinear dots lie on straight line.
v) A dot shows the exact location.
Q.2 From the given figure state which dots are collinear and which are non-collinear.
ii) False. ( A dot has no thickness.)
iv) False ( Non-collinear dots do not lie on straight line.)
Q.2 P and Q, Q and R & P and R are collinear.
P,Q, R are non collinear.