Author note — to cover (Higher)

Higher page, per the A16 braces. Find the tangent to x² + y² = r² at a given point: gradient of the radius to the point, negative reciprocal for the tangent, then the equation through the point. Depends on the perpendicular-lines page. Tangents from an external point are A level. (A16)

Introduction

—coming soon—

Practice and continue

Practice

The tangent to a circle at a point

Finding the tangent’s equation from the radius it is perpendicular to.

Next lesson

Where a line crosses a circle

Substituting the line into the circle’s equation to count the meeting points.