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If |z|

Answer» Correct Answer - Option 1 : less than 2

Concept:

Triangle inequality:

| z+ z | \(\leq\)| z| + | Z2

| cos α | \(\leq\) 1

Calculations:

Given, | z2 + 2z cos α | \(\leq\)| z2 | + | 2z cos α |

We know that, | cos α | \(\leq\) 1

⇒ | z2 + 2z cos α | \(\leq\)| z2 | + | 2z |

Put the value of |z| as  √3 - 1

⇒ | z2 + 2z cos α | < (√3 - 1)+ 2 (√3 - 1)

⇒ | z2 + 2z cos α | < 2 

Hence, If |z| < √3 - 1, then |z2 + 2z cos α| is less than 2



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