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Question 56

A precision-engineered acoustic horn is modeled as a solid of revolution. The internal profile of the horn is defined by the curve C C\,C with equation

y=2x+xxarctan⁡(x) y = \frac{2}{\sqrt{\sqrt{x} + x\sqrt{x}} \arctan(\sqrt{x})} y=x​+xx​​arctan(x​)2​

for 13≤x≤1\frac{1}{3} \le x \le 131​≤x≤1. The region RRR is bounded by the curve CCC, the xxx-axis, and the vertical lines x=13x = \frac{1}{3}x=31​ and x=1x = 1x=1.

The internal volume V V\,V of the horn is formed by rotating the region RRR through 360∘ 360^\circ\,360∘ about the xxx-axis.

Using the substitution tan⁡u=x\tan u = \sqrt{x}tanu=x​,

a.

show that the volume VVV is given by

k∫ab1u2 du k \int_{a}^{b} \frac{1}{u^2} \, du k∫ab​u21​du

where k,ak, ak,a and bbb are constants to be found.

[5]
b.

Hence, using algebraic integration, find the exact value of VVV.

[3]
Markscheme

Integration Questions

  1. A Level
  2. /Maths
  3. /Integration

864 exam-style questions on Edexcel A Level Maths Integration, covering 11.1 Integrating Standard Functions, 11.2 Integrating f(ax + b), 11.3 Using Trigonometric Identities, 11.4 Reverse Chain Rule, 11.5 Integration by Substitution, 11.6 Integration by Parts, 11.7 Partial Fractions, 11.8 Finding Areas, 11.9 The Trapezium Rule, 11.10 Solving Differential Equations, and 11.11 Modelling with Differential Equations. Each one has a worked solution and a mark scheme showing where the marks go.

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