Answer:
D.
Step-by-step explanation:
The point must be a critical point but it could be a saddle point. If the point is a saddle point it would not be neither a maximum nor a minimum. So it must be critical but it does not follow directly that it has a local maximum or local minimum.
Therefore D. (a,b) would be a candidate, but is not necessarily a maximum or minimum. It could be a saddle.
We have:
4 triangles with the base b = 5ft and the height h = 6ft
4 rectangles with the lenght l = 5ft and the width w = 4ft
1 square with side a = 5ft.
The formula of an area of a riangle:

Substitute:

The formula of an area of a rectangle:

Substitute:

The formula of an area of a square:

Substitute:

The Surface Area of composite solid:

Substitute:

<h3>Answer: The Surface Area of the composite solid is 165 ft².</h3>
Step-by-step explanation:
1 kg = 1000 g
4.5 kg = 4.5 × 1000
4500 g
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