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Question : 81 of 120
Marks:
+1,
-0
Solution:
Let
z=(‌| 1+cos‌+i‌sin‌ |
| 1+cos‌−i‌sin‌ |
)72 =(‌| cos‌+i‌sin‌ |
| cos‌−i‌sin‌ |
)72 =‌| cos‌+i‌sin‌ |
| cos‌−i‌sin‌ |
[∵(cos‌θ+i‌sin‌θ)n=cos‌n‌θ+i‌sin‌n‌θ]
=‌| cos‌3‌π+i‌sin‌3‌π |
| cos‌3‌π−i‌sin‌3‌π |
=‌ =1
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