# Secant and tangent of a circle

From Karnataka Open Educational Resources

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

Download this geogebra file from this link.

### 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**

- What is the difference between the secant and a tangent?
- What is the difference between the chord and a secant ?
- Can you draw a secant touching 3 points on the circle ?
- At how many points does a tangent touch a circle ?
- How many tangents can be drawn to a circle ?
- How many tangents can be drawn to a circle at any one given point ?
- How many parallel tangents can a circle have at the most ?