Animated Solution for Mathematics - Complex Numbers: If z1,z2 are complex numbers such that Re(z1)=∣z1−1∣, Re(z2)=∣z2−1∣, and arg(z1−z2)=6π, then Im(z1+z2) is equal to
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Visualized Solution
Introduction to the Complex Plane
Let z=x+iy be a general complex number.
We are given a condition on its real part and its distance from 1.
Decoding the Locus Condition
Given condition: Re(z)=∣z−1∣
Substitute z=x+iy into the condition.
Substituting Coordinates
x=∣(x−1)+iy∣
Simplifying the Equation
x=(x−1)2+y2
Squaring both sides:
x2=(x−1)2+y2
Expanding and Canceling
x2=x2−2x+1+y2
y2=2x−1
Identifying the Locus
The equation y2=2x−1 represents a parabola.
Both z1 and z2 lie on this parabola.
Applying Condition to z1 and z2
Let z1=x1+iy1 and z2=x2+iy2.
y12=2x1−1
y22=2x2−1
Subtracting the Equations
Subtracting the two equations:
y12−y22=2(x1−x2)
Factorizing to Find Slope
(y1−y2)(y1+y2)=2(x1−x2)
x1−x2y1−y2=y1+y22
Using the Argument Condition
Given: arg(z1−z2)=6π
The argument of the difference represents the angle the line joining z1 and z2 makes with the positive real axis.
Equating Slopes
Slope m=tan(6π)=31
Equating the two slope expressions:
31=y1+y22
Final Calculation
Cross-multiplying:
y1+y2=23
Since Im(z1+z2)=y1+y2,
Im(z1+z2)=23
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The Sigma Insight: Geometrical Applications of Complex Numbers
Solution Diagram
Analyzing the Setup
We are given two complex numbers, z1 and z2, satisfying the condition Re(z)=∣z−1∣. Let z=x+iy. The real part is x, and the modulus ∣z−1∣ represents the distance from z to the point (1,0) in the complex plane.
The constraint can be written as:
x=(x−1)2+y2
Squaring both sides yields x2=(x−1)2+y2. Expanding the right side, we obtain:
x2=x2−2x+1+y2
The x2 terms cancel out, leaving us with the equation of a parabola:
y2=2x−1
The Geometry of the Chord
The points z1 and z2 lie on this parabola. We are given that arg(z1−z2)=6π.
The argument of the difference of two complex numbers represents the angle of the vector connecting them. Consequently, the slope m of the chord joining z1 and z2 is:
m=tan(6π)=31
The Elegant Synthesis
For any two points (x1,y1) and (x2,y2) on the parabola y2=2x−1, we can express x as x=2y2+1. The slope of the chord is given by: