Secant and tangent of a circle

A tangent is a line touching a circle in one point. A secant is the line through two distinct points on a circle.

Objectives
To understand tangent and secant of a circle.

Estimated Time
30 minutes

Prerequisites/Instructions, prior preparations, if any

 * The students should have a prior knowledge about a circle and its basic parts and terms.
 * They should know the clear distinction between radius, diameter, chord, secant and tangent.

Materials/ Resources needed

 * Digital : Computer, geogebra	application, projector.
 * Non	digital : Worksheet	and pencil, compass, strings
 * Geogebra	files : Lines	in a circle.ggb

Process (How to do the activity)

 * The teacher can show the geogebra file.
 * Move the points on circumference and explain secant.
 * When both endpoints of secant meet, it becomes a tangent.
 * Name the points on the circumference of the circle.
 * At how many points is the line touching the circle ?
 * What is the line called ?


 * Evaluation Questions
 * 1) What is the difference between the secant and a tangent?
 * 2) What is the difference between the chord and a secant ?
 * 3) Can you draw a secant touching 3 points on the circle ?
 * 4) At how many points does a tangent touch a circle ?
 * 5) How many tangents can be drawn to a circle ?
 * 6) How many tangents can be drawn to a circle at any one given point ?
 * 7) How many parallel tangents can a circle have at the most ?