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2007-10-21 18:04:31 · 5 answers · asked by Ryan S 1 in Science & Mathematics ➔ Mathematics
S.A. = 2 π r ² + 2 π r h
S.A. = 2 π r ( r + h )
S.A. = 12π (6 + 20) cm ²
S.A. = 12π (26) cm ²
S.A. = 980 cm ² (to nearest whole number)
2007-10-22 03:48:58 · answer #1 · answered by Como 7 · 0⤊ 0⤋
The formula for find the TOTAL surface area of a cylinder, including the top and bottom of the shape, is S = 2*pi*r^2 + 2*pi*r*h Where r is the radius of the circle, and h is the height. Since the diameter is 12 cm then the radius is 6 cm. S = 2*pi*r^2 + 2*pi*r*h S = 2*pi*6^2 + 2*pi*6*20 S = 980.18 cm^2 But since it doesnt specify whether you want LATERAL surface area or TOTAL surface area, I will show you how to find the LATERAL surface area also. The formula for lateral surface area (which is the area all around the side, NOT including the top circle and bottom circle), is: S = 2*pi*r*h S = 2*pi*6*20 S = 753.98 cm^2 Since the question does not specify, it is more than likely asking for TOTAL surface area, so the first answer will suffice. Goosey
2016-05-24 02:53:20 · answer #2 · answered by meredith 3 · 0⤊ 0⤋
First you have to determine if this is a closed cylinder or not. If it is a closed cylinder, then you have 2 circles and one lateral surface.
Surface area = 2*pi*r^2 + 2*pi*r*h
= 2*pi*6^2 + 2*pi*6*20
= 979.68 cm^2
2007-10-21 18:15:33 · answer #3 · answered by the DoEr 3 · 0⤊ 0⤋
SA = 2pi*(r^2 ) + 2pi *(r)*(h)
D = 12 ---> r = 6
SA = 2*pi * ( 6^2) + 2*pi*6*20
SA = 72pi + 240pi = 312 pi square cm
or.....980.18 cm^2
this includes the two circular ends on the cylinder, as well as the lateral area [ the area of the side ]
2007-10-21 18:08:38 · answer #4 · answered by Mathguy 5 · 0⤊ 0⤋
= (2 * 3.14159 * [12/2]^2) + (2 * 3.14159 * [12/2] * 20)
= (6.28318 * 6^2) + (6.28318 * 6 * 20)
= (6.28318 * 36) + 753.9818
= 226.19448 + 753.9818
= 980.17628
Answer: 980.17628 sq cm
2007-10-22 02:05:36 · answer #5 · answered by Jun Agruda 7 · 2⤊ 0⤋