Geometry: An Interactive Journey to Mastery

Lesson 23: Three-Dimensional Geometry—Solids

As a leap of faith, you might be willing to say that this formula still

holds for the case with the base of the cone actually being a circle.

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F௘ͽ 6KRZKRZWKHIROORZLQJIRUPXOD

lateral area =^12 × perimeter of base × slant height

translates to the following formula

lateral area = ʌUV

for the case of a circular cone.

r

slant height s

Figure 23.19