All categories

3 years ago

How do I find the area of a circle with the diameter of 4

Mathematics

1 answer:

goblinko [34]3 years ago

7 0

Answer:

use $a = 1/4\pi d^2\\$

all you have to do is plug 4 into d and then square it, and multiply everything together.

Step-by-step explanation:

You might be interested in

An open metal tank of square base has a volume of 123 m^3

snow_lady [41]

Answer:

a) h = 123/x^2

b) S = x^2 +492/x

c) x ≈ 6.27

d) S'' = 6; area is a minimum (Y)

e) Amin ≈ 117.78 m²

Step-by-step explanation:

a) The volume is given by ...

V = Bh

where B is the area of the base, x^2, and h is the height. Filling in the given volume, and solving for the height, we get:

123 = x^2·h

h = 123/x^2

b) The surface area is the sum of the area of the base (x^2) and the lateral area, which is the product of the height and the perimeter of the base.

$S=x^2+Ph=x^2+(4x)\dfrac{123}{x^2}\\\\S=x^2+\dfrac{492}{x}$

c) The derivative of the area with respect to x is ...

$S'=2x-\dfrac{492}{x^2}$

When this is zero, area is at an extreme.

$0=2x -\dfrac{492}{x^2}\\\\0=x^3-246\\\\x=\sqrt[3]{246}\approx 6.26583$

d) The second derivative is ...

$S''=2+\dfrac{2\cdot 492}{x^3}=2+\dfrac{2\cdot 492}{246}=6$

This is positive, so the value of x found represents a minimum of the area function.

e) The minimum area is ...

$S=x^2+\dfrac{2\cdot 246}{x}=(246^{\frac{1}{3}})^2+2\dfrac{246}{246^{\frac{1}{3}}}=3\cdot 246^{\frac{2}{3}}\approx 117.78$

The minimum area of metal used is about 117.78 m².

3 0

3 years ago

Some animals on farms eat hay to get energy. A cow can eat 24 pounds of hay each day. Write and evaluate an expression to find h

vladimir1956 [14]

Answer:

7392 pounds

Step-by-step explanation:

22x24x14

multiplication my friend

7 0

2 years ago

Multiply integer by fraction

ELEN [110]

Make the internet a fraction and then multiply them

3 0

3 years ago

What is the formula for surface area? Giving brainliest to the correct answer

Kitty [74]

Answer: Surface area is the sum of the areas of all faces (or surfaces) on a 3D shape. A cuboid has 6 rectangular faces. To find the surface area of a cuboid, add the areas of all 6 faces. We can also label the length (l), width (w), and height (h) of the prism and use the formula, SA=2lw+2lh+2hw, to find the surface area

5 0

3 years ago

Lee is replacing the carpet in the living room of the house. The living room is a rectangle 20 1/4 feet long 13 1/3 wide. A clos

gtnhenbr [62]

Answer:

100 ft

Step-by-step explanation:

5 0

3 years ago

Read 2 more answers