OCR MEI C1 2011 June — Question 13

Exam BoardOCR MEI
ModuleC1 (Core Mathematics 1)
Year2011
SessionJune
TopicCircles

13 \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{fecb40da-cf47-45e0-801a-1d3d8811b5a0-4_783_766_255_687} \captionsetup{labelformat=empty} \caption{Fig. 13}
\end{figure} Fig. 13 shows the circle with equation \(( x - 4 ) ^ { 2 } + ( y - 2 ) ^ { 2 } = 16\).
  1. Write down the radius of the circle and the coordinates of its centre.
  2. Find the \(x\)-coordinates of the points where the circle crosses the \(x\)-axis. Give your answers in surd form.
  3. Show that the point \(\mathrm { A } ( 4 + 2 \sqrt { 2 } , 2 + 2 \sqrt { 2 } )\) lies on the circle and mark point A on the copy of Fig. 13. Sketch the tangent to the circle at A and the other tangent that is parallel to it.
    Find the equations of both these tangents.