NCERT Class XI Mathematics - Complex Numbers and Quadratic Equations - Solutions

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Question : 47
Total: 52
Find the modulus of
1+i
1−i
−
1−i
1+i

Solution:  
We have,
1+i
1−i
−
1−i
1+i
=
(1+i)2−(1−i)2
(1−i)(1+i)

=
(1−1+2i)−(1−1−2i)
1+1
=
2i+2i
2
=
4i
2
= 2i
∴ |
1+i
1−i
−
1−i
1+i
|
= √22 = 2
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