Mission 2Mission 2

Mission for 2Mission for 2:: To successfully find the

total area of pyramids and cones.

VocabularyVocabulary:: total (surface) area, lateral area, slant height (s)

FormulasFormulas:: L.A. = T.A. = L.A. + A base

2sP

b

Formula for L.A.Formula for L.A.

The formula for the lateral area (L.A.) of a regular pyramid or cone is the half product of its slant height s and the perimeter p of its base.

L.A. = 2sP

b

Formula for S.A.Formula for S.A.

The formula for the surface area (S.A.) of a regular pyramid or cone is the sum of its lateral area and the area of its base (A).

T.A.= L.A.+ Abase

Let’s Try oneLet’s Try one

Find the surface area of a cone with a radius of 10 and a slant height of 13.

Click on “Freckle Boy” Click on “Freckle Boy” afterafter you’ve finished the problem.you’ve finished the problem.

T.A. = L.A. + A base

= + r2

= + r2

= + (10)2

= 408.41 + 314.16

= 722.57 units2

Here is your Answer...Here is your Answer...

2sPb

2sr2

213(10)2

Here is another one!Here is another one!

Find the lateral area of a square pyramid with a slant height of 14 and a base edge of 25.

The answer you have selected is The answer you have selected is incorrect. The correct answer was incorrect. The correct answer was 700. 700.

Don’t worry. . . The little guy has Don’t worry. . . The little guy has the answer!the answer!

Here is your Answer...Here is your Answer...

LA =

=

= 700 units2

2sPb

21425)(4

Pretty slick rick. Keep on Pretty slick rick. Keep on truckin’truckin’

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Exit!Exit!

I hope you’ve I hope you’ve enjoyed enjoyed the show. the show.