Normal to circle at point

Find the equation of the normal (line through centre and point) to a circle at a given point.

4 questions · Moderate -0.4

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Edexcel P2 2023 January Q6
10 marks Moderate -0.3
  1. The circle \(C\) has equation
$$x ^ { 2 } + y ^ { 2 } + 8 x - 4 y = 0$$
  1. Find
    1. the coordinates of the centre of \(C\),
    2. the exact radius of \(C\). The point \(P\) lies on \(C\).
      Given that the tangent to \(C\) at \(P\) has equation \(x + 2 y + 10 = 0\)
  2. find the coordinates of \(P\)
  3. Find the equation of the normal to \(C\) at \(P\), giving your answer in the form \(y = m x + c\) where \(m\) and \(c\) are integers to be found.
AQA C1 2014 June Q6
12 marks Moderate -0.8
6 The diagram shows a curve and a line which intersect at the points \(A , B\) and \(C\). \includegraphics[max width=\textwidth, alt={}, center]{f2124c89-79de-4758-b7b8-ff273345b9dd-7_574_844_349_609} The curve has equation \(y = x ^ { 3 } - x ^ { 2 } - 5 x + 7\) and the straight line has equation \(y = x + 7\). The point \(B\) has coordinates ( 0,7 ).
    1. Show that the \(x\)-coordinates of the points \(A\) and \(C\) satisfy the equation $$x ^ { 2 } - x - 6 = 0$$
    2. Find the coordinates of the points \(A\) and \(C\).
  1. Find \(\int \left( x ^ { 3 } - x ^ { 2 } - 5 x + 7 \right) \mathrm { d } x\).
  2. Find the area of the shaded region \(R\) bounded by the curve and the line segment \(A B\).
    [0pt] [4 marks] \(7 \quad\) A circle with centre \(C\) has equation \(x ^ { 2 } + y ^ { 2 } - 10 x + 12 y + 41 = 0\). The point \(A ( 3 , - 2 )\) lies on the circle.
CAIE P1 2024 November Q8
10 marks Moderate -0.3
The equation of a circle is \(x^2 + y^2 + px + 2y + q = 0\), where \(p\) and \(q\) are constants.
  1. Express the equation in the form \((x - a)^2 + (y - b)^2 = r^2\), where \(a\) is to be given in terms of \(p\) and \(r^2\) is to be given in terms of \(p\) and \(q\). [2]
The line with equation \(x + 2y = 10\) is the tangent to the circle at the point \(A(4, 3)\).
    1. Find the equation of the normal to the circle at the point \(A\). [3]
    2. Find the values of \(p\) and \(q\). [5]
Edexcel C2 Q8
9 marks Moderate -0.3
The circle \(C\), with centre at the point \(A\), has equation \(x^2 + y^2 - 10x + 9 = 0\). Find
  1. the coordinates of \(A\), [2]
  2. the radius of \(C\), [2]
  3. the coordinates of the points at which \(C\) crosses the \(x\)-axis. [2]
Given that the line \(l\) with gradient \(\frac{7}{T}\) is a tangent to \(C\), and that \(l\) touches \(C\) at the point \(T\),
  1. find an equation of the line which passes through \(A\) and \(T\). [3]