Line-circle intersection points

Find the coordinates where a given line intersects a circle by solving simultaneous equations.

27 questions · Moderate -0.4

1.03d Circles: equation (x-a)^2+(y-b)^2=r^2
Sort by: Default | Easiest first | Hardest first
WJEC Unit 1 2022 June Q7
11 marks Standard +0.3
A circle \(C\) has centre \(A\) and equation \(x^2 + y^2 - 4x - 6y = 3\).
  1. Find the coordinates of \(A\) and the radius of \(C\). [3]
The line \(L\) with equation \(y = x + 5\) intersects \(C\) at the points \(P\) and \(Q\).
  1. Determine the coordinates of \(P\) and \(Q\). [4]
  2. The point \(B\) is on \(PQ\) and is such that \(AB\) is perpendicular to \(PQ\). Find the length of \(PB\). [2]
  3. Show that the area of the smaller segment enclosed by \(C\) and \(L\) is \(4\pi - 8\). [2]
SPS SPS SM Pure 2022 June Q3
10 marks Easy -1.2
A circle has centre \(C(3, -8)\) and radius \(10\).
  1. Express the equation of the circle in the form $$(x - a)^2 + (y - b)^2 = k$$ [2 marks]
  2. Find the \(x\)-coordinates of the points where the circle crosses the \(x\)-axis. [3 marks]
  3. The line with equation \(y = 2x + 1\) intersects the circle.
    1. Show that the \(x\)-coordinates of the points of intersection satisfy the equation $$x^2 + 6x - 2 = 0$$ [3 marks]
    2. Hence show that the \(x\)-coordinates of the points of intersection are of the form \(m \pm \sqrt{n}\), where \(m\) and \(n\) are integers. [2 marks]