# Surface area of a cylinder

From Karnataka Open Educational Resources

The shape can be thought of as a circular prism. Cylinder could be closed or open. Surface areas for a cylinder is investigated.

### Objectives

To find surface area of a cylinder

### Estimated Time

40 minutes.

### Prerequisites/Instructions, prior preparations, if any

- The cylinder is a 3 dimensional solid having curved lateral surface with two circular surfaces on either sides.
- Basics of circle and rectangle.
- Formula to find the area of a circle and a rectangle.

### Materials/ Resources needed

Digital: Laptop, internet link, projector and a pointer.

Geogebra file:

Download this geogebra file from this link.

### Process (How to do the activity)

- The teacher can initially discuss about cylinder as a shape and explain its parts.
- She can then talk about what area means.
- Discuss regarding surfaces to be covered in deriving the formula for surface area of the cylinder.
- Project the video and discuss.

Developmental Questions:

- Can youn identify the shapes of the open cylinder?
- What is the radius of the circle ?
- What is the formula to find the circumference of the circle.
- Into what shape does the curved surface of the cylinder opens ?
- What are the measures of height and breadth of the rectangle?
- What is the formula to find the area of the rectangle ?

- Evaluation:

- Can you explain the conversion of circumference of the circle into the length of the rectangle ?

- Question Corner:

- What is the difference between lateral and total surface area ?
- What are the formulae for lateral surface area and total surface area ?
- Name a few situations wherin one may have to find only the lateral surface area of the cylindrical object ?