Which has a larger surface area a prism or a cylinder? Explain
1 answer:
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Answer:
length of rectangle = 5
width of rectangle = 5
Area of rectangle = 25
Step-by-step explanation:
Since the length of the rectangle is "x", and the value of the area is given by the product of the length "x" times the width "10-x", indeed, the area "y" of the rectangle is given by the equation:
Now, they tell us that the area of the rectangle is such that coincides with the maximum (vertex) of the parabola this quadratic expression represents. So in order to find the dimensions of the rectangle and therefore its area, we find the x-coordinate for the vertex, and from it, the y-coordinate of the vertex, which is the rectangle's actual area.
Recall that the formula for the x of the vertex of a quadratic of the form :
is given by the formula:
which in our case gives:
Therefore, the length of the rectangle is 5, and its width (10-x) is also 5.
The area of the rectangle is therefore the product of these two values: 5 * 5 = 25
Which should coincide with the value we obtain when we replace x by 5 in the area formula:
Answer:
Cost = 616000 DHS per square centimetre.
Step-by-step explanation:
curved surface of a cylinder = 2rh
r = 7 cm
h = 1400 m = 140000 cm
The outer curved surface area of the cylinder = inner curved surface area of the cylinder
The inner curved surface of the cylinder = 2rh
= 2 x x 7 x 140000
= 2 x 22 x 1 x 140000
= 6160000
The inner curved surface of the cylinder is 6160000 square centimetre.
But, the cost of painting is at the rate of 10 DHS per square centimetre.
The inner curved surface of the cylinder = 6.16 x square centimetre.
cost of painting the inner curved surface area =
= 616000 DHS per square centimetre
The cost of painting the inner surface is 616000 DHS per square centimetre.