A laboratory-grown synthetic crystal takes the form of a regular tetrahedron, which consists of 4 congruent equilateral triangular faces meeting at 4 vertices. The side length of the tetrahedron is denoted by L mmL\text{ mm}L mm.
Show that the total surface area, S mm2S\text{ mm}^2S mm2, of the tetrahedron is given by
S=3L2 S = \sqrt{3}L^2 S=3L2Given that the volume, V mm3V\text{ mm}^3V mm3, of the tetrahedron is given by
V=L362 V = \frac{L^3}{6\sqrt{2}} V=62L3show that dVdS=624L\dfrac{\text{d}V}{\text{d}S} = \dfrac{\sqrt{6}}{24}LdSdV=246L.
The surface area of the crystal is increasing at a constant rate of 0.14 mm2 s−10.14\text{ mm}^2\text{ s}^{-1}0.14 mm2 s−1.
Find the rate of change of the volume of the crystal when L=6L = 6L=6, giving your answer to 2 significant figures.
Practise Edexcel A Level Maths Differentiation with exam-style questions for A Level Maths. 311 questions covering 9.1 Differentiating sin x and cos x, 9.2 Differentiating exponentials and logarithms, 9.3 The Chain Rule, 9.4 The Product Rule, 9.5 The Quotient Rule, 9.6 Differentiating Trigonometric Functions, 9.7 Parametric Differentiation, 9.8 Implicit Differentiation, 9.9 Using Second Derivatives, and 9.10 Rates of Change, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
