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606 ⏐⏐⏐ THE BASIC ELEMENTS AND PHASORS<br />

C 1<br />

8 �120° 8<br />

b. � ��� � � / 120° � (�50°) � 0.5 �170°<br />

C2 16 ��50° 16<br />

We obtain the reciprocal in the rectangular form by multiplying the<br />

numerator and denominator by the complex conjugate of the denominator:<br />

1<br />

�<br />

X � jY<br />

1<br />

�<br />

X � jY<br />

� � �� � �<br />

1 X Y<br />

and � ��2 2 � j �2 2<br />

(14.36)<br />

X � jY X � Y X � Y<br />

In polar form, the reciprocal is<br />

X � jY<br />

�<br />

X � jY<br />

1 1<br />

� � � ��v (14.37)<br />

Z �v Z<br />

A concluding example using the four basic operations follows.<br />

EXAMPLE 14.26 Perform the following operations, leaving the answer<br />

in polar or rectangular form:<br />

a. �<br />

�<br />

�<br />

� � 0.983 � j0.207<br />

b. � �<br />

� 35.35 / 75° � (�20°) � 35.35 �95°<br />

(2 �20°) (2 �20°)(2 �20°)(5 �53.13°)<br />

c. �����<br />

10 ��36.87°<br />

(4 �40°)(5 �53.13°) 20 �93.13°<br />

���� ���<br />

10 ��36.87° 10 ��36.87°<br />

� 2 / 93.13° � (�36.87°) � 2.0 �130°<br />

d. 3 �27° � 6 ��40° � (2.673 � j 1.362) � (4.596 � j 3.857)<br />

� (2.673 � 4.596) � j (1.362 � 3.857)<br />

2 [(6)(4) � (9)(10)] � j [(4)(9) � (6)(10)]<br />

�����<br />

4<br />

114 � j 24<br />

��<br />

116<br />

(50 �30°)(5 � j 5) (50 �30°)(7.07 �45°) 353.5 �75°<br />

�� ��� ��<br />

10 ��20°<br />

10 ��20° 10 ��20°<br />

(3 � j 4)<br />

��<br />

8 � j 6<br />

2 � 10 2<br />

(2 � j 3) � (4 � j 6) (2 � 4) � j (3 � 6)<br />

��� ���<br />

(7 � j 7) � (3 � j 3) (7 � 3) � j (7 � 3)<br />

(6 � j 9)(4 � j 10)<br />

���<br />

(4 � j 10)(4 � j 10)<br />

� �1.923 � j 5.219<br />

X � jY<br />

� X 2 � Y 2<br />

14.11 CALCULATOR AND COMPUTER<br />

METHODS WITH COMPLEX NUMBERS<br />

The process of converting from one form to another or working through<br />

lengthy operations with complex numbers can be time-consuming and<br />

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