Q. 83.7( 3 Votes )

# If is purely imaginary and z = –1, show that |z| = 1.

Answer :

Let z= a + ib

Now,

Given that is purely imaginary ⇒ real part = 0

⇒ a^{2} + b^{2} - 1 = 0

⇒ a^{2} + b^{2} = 1

⇒ |z| = 1

Hence proved.

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