Question

Write the formula to find total surface area of pen holder (cylinder opened one side)

Answer 1

total surface area of pen holder is

πr( r+2h)

•let a cylinder with base of radius r & height h

•Total surface area of cylinderical pen holder includes area of base (cicular) & curved surface area of cylinder.

•As, it is open from top , we will not include upper circular region in total surface area

•TSA = πr² + 2πrh

•taking πr common

TSA = πr( r + 2h )

•hence required surface area of cylinderical pen holder is πr( r + 2h )

Answer 2

Required Formula is $\pi r(r+h)$

Step-by-step explanation:

Let us suppose that the Height of Cylinder be h units and radius of base of cylinder be r units.

Since the base of cylinder is circular, So Area of base = $\pi r^2$  """(a)

Now, area of curved surface = circumference of circle \times the height of cylinder

= $2\pi r \times h$ """(b)

• So, Total Surface Area of Cylinder = Sum of (a) and (b)

= Area of Base + Area of Curved Surface

= $\pi r^2 + 2\pi r \times h$

= $\pi r(r+h)$ is the Formula for one side opened Cylinder.