JEE Main · Mathematics ↓ Falling

Complex Numbers appeared 41 times across 3 years — 4.7% of Mathematics. This question is from Geometry of Complex Numbers.

Year 2026 2025 2024 Total
Questions 11 16 14 41

Let z be the complex number satisfying |z-5|≤ 3 and having maximum positive principal argument. Then 34|(5z-12)/(5iz+16)|² is equal to:

Solution & Explanation

Related Formula
For maximum argument of z on a circle, the ray from origin is tangent to the circle. If |z-a| ≤ r, maximum argument implies θ = (r)/(|a|) and coordinates are x=a ²θ, y=a θ θ
Core Logic

Complex geometry maximum argument diagram for Q19 - JEE Main 2026 Evening
Complex geometry maximum argument diagram for Q19 - JEE Main 2026 Evening
The condition |z-5|≤ 3 represents a disk centered at (5,0) with radius 3. To maximize the principal argument θ, the ray from origin must touch the circle in the first quadrant. The tangent, origin, and center form a right-angled triangle.

Step 1: Locate the Point z

From geometry, hypotenuse c = 5, opposite (radius) r = 3. The adjacent side (length of tangent) is √(5² - 3²) = 4. The angle of tangency θ satisfies θ = (3)/(5) and θ = (4)/(5). The point P(z) lies on the circle and the tangent ray:

z ≡ (4 θ, 4 θ) = (4((4)/(5)), 4((3)/(5))) = ((16)/(5), (12)/(5)) z = (16)/(5) + (12)/(5)i
Step 2: Evaluate the Target Expression

We need 34|(5z - 12)/(5iz + 16)|². Substitute 5z = 16 + 12i: Numerator: 5z - 12 = 16 + 12i - 12 = 4 + 12i Denominator: 5iz + 16 = i(16 + 12i) + 16 = 16i - 12 + 16 = 4 + 16i Expression:

34 |(4 + 12i)/(4 + 16i)|² = 34 (|4 + 12i|²)/(|4 + 16i|²) = 34 (4² + 12²)/(4² + 16²) = 34 ((16 + 144)/(16 + 256)) = 34 ((160)/(272)) = (34 × 160)/(272) = (5440)/(272) = 20
Pattern Recognition

For maximum (z) on |z-c| = r where c is real, z coordinates are given by geometric projection: z = √(c²-r²)( θ + i θ) where θ = r/c.

Chapter Mix

Class 11 Maths: Complex Numbers

Reference Study Guides

More Complex Numbers Previous-Year Questions — Page 9

Q26 jee_main_2024_31_jan_morning Properties of Modulus and Argument
If α denotes the number of solutions of |1 - i|^x = 2^x and β = ((|z|)/( (z))), where z = (π)/(4) (1 + i)⁴ ( 1 - √(π) i√(π) + i + √(π) - i1 + √(π) i), i = √(-1), then the distance of the point (α, β) from the line 4x - 3y = 7 is
Numerical Answer. Answer: 3 to 3

Solution

Core Logic
|1 - i|^x = 2^x (√(2))^x = 2^x 2x/2 = 2^x

This implies (x)/(2) = x x = 0. There is exactly 1 solution, so α = 1.

Step 1: Simplify complex number z
(1+i)⁴ = ((1+i)²)² = (1 + i² + 2i)² = (2i)² = -4

Thus, z = -π ( (1-√(π)i)(√(π)-i)π + 1 + (√(π)-i)(1-√(π)i)1 + π )

Step 2: Simplify Bracket

Let's expand the terms directly: z = (π)/(4)(-4) [ √(π) - π i - i - √(π)π + 1 + √(π) - i - π i - √(π)1 + π ]

= -π [ (-i(π+1))/(π+1) + (-i(π+1))/(π+1) ] = -π [ -i - i ] = 2π i
Step 3: Find beta

For z = 2π i: |z| = 2π and (z) = (π)/(2).

β = (|z|)/( (z)) = (2π)/(π/2) = 4
Step 4: Distance from Line

Distance of point (α, β) = (1, 4) from the line 4x - 3y - 7 = 0:

D = |4(1) - 3(4) - 7|√(4² + (-3)²) = (|4 - 12 - 7|)/(5) = (|-15|)/(5) = 3
Chapter Mix

Class 11 Maths: Complex Numbers and Quadratic Equations Class 11 Maths: Straight Lines

More Complex Numbers Questions — jee_main_2026_21_jan_evening

Practice all Complex Numbers previous-year questions →

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