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Question #40513

Difficulty: 8/10 | 🟢 Free

The Question

The Argand plane C\mathbb{C} is embedded in R3\mathbb{R}^3 as the plane Π:z=3x\Pi: z = \sqrt{3}x. The origin of C\mathbb{C} maps to (0,0,0)(0,0,0). The real axis of C\mathbb{C} coincides with the line of intersection of Π\Pi and the xzxz-plane, with the positive real direction having positive xx. The imaginary axis of C\mathbb{C} coincides with the yy-axis. Let RR be the region in C\mathbb{C} defined by the inequalities ∣w∣≤2|w| \le 2 and log⁡∣w∣(∣w−2∣)≤1\log_{|w|}(|w - 2|) \le 1. A solid SS in R3\mathbb{R}^3 is bounded below by the xyxy-plane (z=0z=0), above by the plane z=23x+5z = 2\sqrt{3}x + 5, and laterally by the vertical cylinder passing through the boundary of the orthogonal projection of RR onto the xyxy-plane. Find the volume of the solid SS.

Options

  • A.

    3+35π6−5323 + \frac{35\pi}{6} - \frac{5\sqrt{3}}{2}

  • B.

    3+10π3−5323 + \frac{10\pi}{3} - \frac{5\sqrt{3}}{2}

  • C.

    6+35π3−536 + \frac{35\pi}{3} - 5\sqrt{3}

  • D.

    6+20π3−536 + \frac{20\pi}{3} - 5\sqrt{3}

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Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Bridge

Practice problems that bridge the gap between foundational theory and advanced practical application.

Concepts Behind This Question

Geometry of Complex Inequalities|Line-Plane intersection logic|Region Ambiguity

Why This Question Is Tricky

Common Mistakes

This question tests the 'Region Ambiguity' trap by embedding a complex inequality into a 3D volumetric projection.

Students typically solve log⁡∣w∣(∣w−2∣)≤1\log_{|w|}(|w - 2|) \le 1 by assuming the base ∣w∣>1|w| > 1, yielding the region u≥1u \ge 1.

They critically fail to consider the case where the base 0<∣w∣<10 < |w| < 1, which flips the inequality to ∣w−2∣≥∣w∣  ⟹  u≤1|w - 2| \ge |w| \implies u \le 1, adding the entire punctured unit disk to the locus.

This omission leads to a massive mismatch in the integration limits.

Furthermore, mapping the Argand plane to a skewed 3D plane z=3xz = \sqrt{3}x forces a coordinate transformation (Jacobian =1/2= 1/2) before integrating the volumetric cross-section, punishing rote memorization of 2D area formulas.

Quick Facts About This Question

Question Information

SubjectMathematics
ChapterComplex Numbers and Quadratic Equations - Class 11
ConceptGeometry of Complex Inequalities
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree