Formulas for Various Areas

Formulas for Various Areas

Plane Figures Area1
triangle ab /2
parallelogram ab
rectangle ab
square s 2
circle π r 2
Solids Total Surface Area1
right circular cylinder 2π r ( r  +  a )
right circular cone π r ( r  +  l )
sphere 4π r 2
1 The abbreviations used are: b = base (length of any side of a plane figure); a = altitude (perpendicular distance from the farthest point of the figure to the extended base); s = side; r = radius (of the base circle in the case of the cylinder or cone); l = slant height (distance from vertex to base of a cone measured on its surface).

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

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