Volume and Surface Area of ​​Cylinder

In geometry, tube or cylinder is built of three-dimensional space formed by two identical parallel circle and a rectangle that surrounds the circle. The cylinder has three sides and two ribs. Both of the circle is called the base and lid, blanket which enveloped the tube is an rectangle.

• The tube consists of the base and curved sides (covers); 
• The top and base are congruent circular;
• Lines EA, EB and EC is the radius of the tube;
• The line AB is the diameter of the tube;
• AG dan BF is the height of the tube.

Area of Blanket

To determine the cylinder blanket by opening the cylinder without the top and base sides. so a rectangle formed.

• Length of rectangle = circumference of the cylinder base (circle)  = 2 πr 
• Width = cylinder height (h)

Then the cylinder area:

= Area of ​​rectangle

= 2πr h

Example :

Radius of cylinder is 20 cm. If height of cylinder 15 cm and π =3,14. What is area of blanket ?

Area = 2πr x h

        = 2 x 3,14 x 20 x 15

        = 6,28 x 20 x 15

        = 125,6 x 15

        = 1.884 cm 2

• Surface area of cylinder

Surface area cylinder is the sum of the cylinder blanket area, which is a rectangular with the upper and bottom side of the cylinder which is a circle.

Area = 2πr(h +r)

            = 2 x 3,14 x 20 (15+20)

         = 6,28 x 20 (35)

         = 125,6 x 35

            = 4.396 cm2

• Volume of cylinder 

Cylinder is a prism whose base is a circle, so to calculate the volume of the cylinder can be used prism volume 

Volume = πr2 h

              = 3,14 x 20 x 20 x 15

              = 6,28 x 20 x 15

              = 1.256 x 15

              = 18.840 cm3