Page 77 - Start Up Mathematics_6

Example 1: In the adjoining figure name:

(a) Four collinear points (b) A line C B
(c) Four rays (d) Five line segments O
P
E
Solution: (a) The four collinear points are A, E, O and B. A
(b) AB , is a line. However, it can be written in different ways.
(c) Four rays are OB, OC, OE and OP . However, many answers are possible.

(d) Five line segments are OB, OC, OA, OE and AE. However, many answers are
possible.

Example 2: Name the given line in all possible (twelve) ways, choosing only two letters at a
time from the four given. (NCERT)

A B C D
Solution: Following are the possible ways to name the given line:
AB, AC, AD, BC, BD, CD, DC, DB, CB, DA, CA and BA.

Example 3: Use the figure to name:
(a) Lines containing point B C F
(b) Line passing through D E
(c) Line on which C lies A B D
(d) Two pairs of intersecting lines O
(e) Rays having E as starting point
Solution: (a) Lines containing point B are AE and CO.
(b) Line passing through D is BE.
(c) Line on which C lies is BO.
(d) Two pairs of intersecting lines are AE and OC; AE and EF.
(e) Rays having E as starting point are EF and ED.

MATHS LAB ACTIVITY

Objective: To know the number of lines passing through (a) one point and (b) two points
Material required: Drawing sheets, a pencil, a ruler

Demonstration:
Step 1: Mark two points P and Q on a white sheet P Q
of paper.
Step 2: Fold the paper so that the crease passes P Q
through the point P.

Step 3: Keep folding the paper in different directions
so that each crease passes through the point P. Q

Step 4: Repeat steps 2 and 3 for the point Q. P
Observation: There are unlimited lines passing through P or Q, but only one line passes
through P and Q.
Inference: Infinite lines can pass through one point and only one line passes through two points.

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