Paper 2 · Co-ordinate Geometry of the Circle
⏱ Tested in 1 exam question since 2020
Lesson 8 of 9
The circle 8 : Find the equation of the tangent to the circle from the point.
This tutorial is for members
Read the lesson notes free below — subscribe to watch the full worked video and download the PDF.
Subscribe for full access · €199/yrYou’ll learn
- Write a generic line through the external point with unknown slope m
- Solve for the two slopes by setting perpendicular distance from centre = radius
- Square both sides to clear the modulus and surd, then solve the quadratic in m
- Find a tangent's length via Pythagoras: (tangent)² + r² = (centre-to-point)²
Most recent exam questions
- 2020 P2 Q2(a)
💬 Stuck on something in this lesson?
Send your question with this lesson’s name attached — you’ll get a reply by email.