The profile of a high-precision cooling fin for a microchip is modeled by a curve with parametric equations
x=36−6τ,y=τ336+6τ,0≤τ≤6 x = \sqrt{36 - 6\tau}, \quad y = \dfrac{\tau^3}{\sqrt{36 + 6\tau}}, \quad 0 \le \tau \le 6 x=36−6τ,y=36+6ττ3,0≤τ≤6A cross-section of the fin, region RRR, is bounded by this curve, the xxx-axis, and the yyy-axis. The curve touches the xxx-axis at τ=0\tau = 0τ=0 and meets the yyy-axis at τ=6\tau = 6τ=6.
Show that the area of R R\,R is given by
K∫06τ31296−36τ2 dτ K \int_{0}^{6} \dfrac{\tau^3}{\sqrt{1296 - 36\tau^2}} \, d\tau K∫061296−36τ2τ3dτwhere K K\,K is a constant to be found.
Using the substitution u=1296−36τ2u = 1296 - 36\tau^2u=1296−36τ2, or otherwise, determine the exact area of RRR.
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.