# EX 1. MAXIMUM VOLUME FOR A GIVEN SURFACE AREA Tom has 40m 2 of plastic sheeting to build a greenhouse in the shape of a square-based prism. What are the.

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EX 1. MAXIMUM VOLUME FOR A GIVEN SURFACE AREA Tom has 40m 2 of plastic sheeting to build a greenhouse in the shape of a square-based prism. What are the dimensions that will provide the maximum volume, assuming she must cover all six sides with sheeting?

Insert ‘h’ into Volume equation This equation will allow us to determine MAX volume

 We ignore negative pts  Maximum volume of cylinder is at the top of the curve:  (3, 16.5)  Interpretation: A base length of 3 gives a maximum volume for the cylinder of 16.5m 3 whose surface area is 40m 2.

>What could go wrong with our answer? >We could be missing the maximum point by a bit >Solution? Plot more points >With new graph, max point is now (2.5,17.1875) instead of (3, 16)

An outdoor sporting goods manufacturer is designing a new tent in the shape of an isosceles right triangular prism. To maintain the shape of this prism, the base of the triangular face must always be double its height.

To fit 5 people comfortably with gear, the volume inside the tent needs to be 600 ft 3. What dimensions will give this tent a minimum surface area? Front SideBottom b = 2h h l We use the fact that b = 2h to reduce the number of variables x

Front SideBottom b = 2h h l x

Front SideBottom b = 2h h l x h h x A SIDE = 1.41hl TOTAL Surface Area SA = 2(A FRONT )+A BOTTOM +2(A SIDE ) =2(h 2 )+2hl+2(1.41hl) SA = 2h 2 + 4.83hl

Now need to substitute this expression for ‘l’ into the equation for Minimum Surface Area

(h=9, SA=484)

 p. 60 #2, 6, 7, 9, 12

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