If z 1 ,   z 2 are complex numbers such that Re z 1 = z 1 - 1 and Re z 2 = z 2 - 1 and arg z 1 - z 2 =…

If z1, z2 are complex numbers such that Rez1=z1-1 and Rez2=z2-1 and argz1-z2=π6, then Imz1+z2 is equal to :

  1. 23
  2. 32
  3. 13
  4. 23

Solution

Let z1 =x1+iy1 and z2=x2+iy2

Given z1-1=Rez1

x1-12+y12=x12

y12-2x1+1=0 ..............1

z2-1=Rez2

x2-12+y22=x22

y22 -2x2+1=0 ...........2

Subtracting equation 2 from equation 1, we get

y12-y22-2x1-x2=0

y1-y2 y1+y2=2x1-x2

y1+y2=2x1-x2y1-y2 ............3

Also given, arg z1-z2=π6

tan-1y1-y2x1-x2=π6

y1-y2x1-x2=13 .........4

Putting equation 4 in equation 3, we get

y1+y2=23Imz1+z2=23

Asked in: JEE Main 2020 (03 Sep Shift 2)

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