OCR FP2 2009 January — Question 3 7 marks

Exam BoardOCR
ModuleFP2 (Further Pure Mathematics 2)
Year2009
SessionJanuary
Marks7
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicIntegration using inverse trig and hyperbolic functions
TypeDerivative of inverse trig function
DifficultyStandard +0.3 Part (i) is a standard FP2 proof requiring implicit differentiation of y = sin⁻¹x, which is bookwork. Part (ii) applies implicit differentiation to a given equation—straightforward application once you differentiate both inverse sine terms. The calculation at x=1/4 requires care with surds but follows directly. This is a routine FP2 question testing standard techniques without requiring novel insight, making it slightly easier than average overall.
Spec1.05i Inverse trig functions: arcsin, arccos, arctan domains and graphs1.07s Parametric and implicit differentiation

  1. Prove that the derivative of \(\sin^{-1} x\) is \(\frac{1}{\sqrt{1-x^2}}\). [3]
  2. Given that $$\sin^{-1} 2x + \sin^{-1} y = \frac{1}{2}\pi,$$ find the exact value of \(\frac{dy}{dx}\) when \(x = \frac{1}{4}\). [4]

\begin{enumerate}[label=(\roman*)]
\item Prove that the derivative of $\sin^{-1} x$ is $\frac{1}{\sqrt{1-x^2}}$. [3]

\item Given that
$$\sin^{-1} 2x + \sin^{-1} y = \frac{1}{2}\pi,$$
find the exact value of $\frac{dy}{dx}$ when $x = \frac{1}{4}$. [4]
\end{enumerate}

\hfill \mbox{\textit{OCR FP2 2009 Q3 [7]}}