A circle has equation . Find the equation of the tangent to the circle at the point .

Answer and explanation

Correct answer: A.

  1. Step 1: Identify the centre of the circle as and compute the gradient of the radius : .
  2. Step 2: The tangent line is perpendicular to the radius at the point of tangency, so its gradient is .
  3. Step 3: Write the equation of the tangent through : .
Answer
.

Practise more Straight Lines, Circles and Coordinate Geometry.

Free questions with an explanation for every one, and full timed Scottish Highers mock tests.