Page 38 - Mathematics Class - XI

Unit II Algebra
Algebra

TOPIC - 4: Complex Number

ACTIVITY 4.1

OBJECTIVE
To interpret geometrically the meaning of i = −1 and its integral powers.

MATERIAL REQUIRED
 Hard board  Compass
 White chart paper  Glue

 Pencil or sketch pen  Nails
 Ruler  Thread

PRE-REQUISITE KNOWLEDGE
1. Knowledge of coordinate geometry
2. Knowledge of complex number iota (i) and its properties

PROCEDURE

1. Take a piece of hardboard of convenient size and paste a white chart paper on it.
2. Draw two mutually perpendicular lines X′OX and Y′OY representing the coordinate axes as shown in
Fig. (a).
3. Take a thread of a unit length representing the number 1 along OX. Fix one end of the thread to the nail at
O and the other end at M as shown in Fig. (b).

4. Loosen the other end of the thread at M and rotate the thread through angles of 90°, 180°, 270° and 360°
and mark the free end of the thread in different cases as M , M , M and M respectively, as shown in
1
2
4
3
Fig. (b).
Y Y
M
1

M
X′ X X′ X
O M O M
2 4

M
3

Y′ Y′
Fig. (a) Fig. (b)

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