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9.7 Parametric Differentiation

9.7 Parametric Differentiation

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Question 14

A parabolic acoustic mirror for a long-range microphone is modeled by the parametric equations

x=5t2 and y=10t,−3≤t≤3 x = 5t^2 \text{ and } y = 10t, \quad -3 \le t \le 3 x=5t2 and y=10t,−3≤t≤3
a.

Determine a Cartesian equation for the profile of the mirror in the form y2=f(x)y^2 = f(x)y2=f(x).

[2]
b.

A sound sensor is located at point B(5,0)B(5, 0)B(5,0). A specific point AAA on the mirror's profile corresponds to the parameter t=at = at=a, where a>1a > 1a>1. The tangent to the mirror at AAA makes an angle θ\thetaθ with a line through AAA parallel to the xxx-axis. The line segment ABABAB makes an angle ϕ\phiϕ with the positive xxx-axis.

(i) By finding an expression for dydx\frac{dy}{dx}dxdy​ in terms of ttt, show that tan⁡θ=1a\tan \theta = \frac{1}{a}tanθ=a1​.

(ii) Find tan⁡ϕ\tan \phitanϕ in terms of aaa.

(iii) Hence, prove that tan⁡2θ=tan⁡ϕ\tan 2\theta = \tan \phitan2θ=tanϕ.

[7]
Markscheme

9.7 Parametric Differentiation Questions

  1. A Level
  2. /Maths
  3. /9.7 Parametric Differentiation

35 exam-style questions on Edexcel A Level Maths 9.7 Parametric Differentiation. Each one has a worked solution and a mark scheme showing where the marks go.

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