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Question

Mathematics Question on complex numbers

Let OO be the origin and AA be the point z1=1+2iz _1=1+2 i. If BB is the point z2,Re(z2)<0z _2, \operatorname{Re}\left( z _2\right)<0, such that OABOAB is a right angled isosceles triangle with OBOB as hypotenuse, then which of the following is NOT true ?

A

argz2=πtan13\arg z _2=\pi-\tan ^{-1} 3

B

arg(z12z2)=tan143\arg \left( z _1-2 z _2\right)=-\tan ^{-1} \frac{4}{3}

C

z2=10\left|z_2\right|=\sqrt{10}

D

2z1z2=5\left|2 z_1-z_2\right|=5

Answer

2z1z2=5\left|2 z_1-z_2\right|=5

Explanation

Solution

The correct option is (D): 2z1z2=5\left|2 z_1-z_2\right|=5