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alexira [117]
3 years ago
6

How do I work this out?

Mathematics
2 answers:
marin [14]3 years ago
4 0
Area of a full circle is: PI x r^2

so full circle is 4^2 x PI = 16PI

the shaded part is 3/4 of the circle

16 x 3/4 = 12
 so 12 PI ft^2 is shaded

Vikentia [17]3 years ago
3 0
First, find the area of the circle as a whole. Then find the percentage or fraction of that area.

STEP ONE

As you probably know, you use this formula to find the area of any circle.

A=\pir^2

We know what the radius is, so substitute the 4 for the r in the formula.

A=4^2\pi

Simplify.

A=4^2\pi
A=16\pi

STEP TWO

Now that we know what the area of the circle is as a whole, let's find the fraction of that area. We want to the know the area of the shaded part.

Multiply the area by 3/4.

(16\pi)(3/4)
(48\pi)/4
12\pi

So, the answer is the first option.
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An English teacher needs to pick 4 books to put on his reading list for the next school year. He has narrowed down his choices t
Marina86 [1]

Answer:

A) 3 ways

B) sorry don't know.

Step-by-step explanation:

2 P and 2 N

3P and 1 N

4P

So 3 ways.

7 0
3 years ago
The expression 3P2 represents the number of ways of:?
Vsevolod [243]
The expression 3P2 can also be read as "permutation of 3 taken 2". This represents the number of ways in which the 3 items are arranged with the emphasis on the arrangement of the first two other items. 
5 0
3 years ago
Read 2 more answers
The equation giving a family of ellipsoids is u = (x^2)/(a^2) + (y^2)/(b^2) + (z^2)/(c^2) . Find the unit vector normal to each
Fynjy0 [20]

Answer:

\hat{n}\ =\ \ \dfrac{\dfrac{x}{a^2}\hat{i}+\ \dfrac{y}{b^2}\hat{j}+\ \dfrac{z}{c^2}\hat{k}}{\sqrt{(\dfrac{x}{a^2})^2+(\dfrac{y}{b^2})^2+(\dfrac{z}{c^2})^2}}

Step-by-step explanation:

Given equation of ellipsoids,

u\ =\ \dfrac{x^2}{a^2}+\dfrac{y^2}{b^2}+\dfrac{z^2}{c^2}

The vector normal to the given equation of ellipsoid will be given by

\vec{n}\ =\textrm{gradient of u}

            =\bigtriangledown u

           

=\ (\dfrac{\partial{}}{\partial{x}}\hat{i}+ \dfrac{\partial{}}{\partial{y}}\hat{j}+ \dfrac{\partial{}}{\partial{z}}\hat{k})(\dfrac{x^2}{a^2}+\dfrac{y^2}{b^2}+\dfrac{z^2}{c^2})

           

=\ \dfrac{\partial{(\dfrac{x^2}{a^2})}}{\partial{x}}\hat{i}+\dfrac{\partial{(\dfrac{y^2}{b^2})}}{\partial{y}}\hat{j}+\dfrac{\partial{(\dfrac{z^2}{c^2})}}{\partial{z}}\hat{k}

           

=\ \dfrac{2x}{a^2}\hat{i}+\ \dfrac{2y}{b^2}\hat{j}+\ \dfrac{2z}{c^2}\hat{k}

Hence, the unit normal vector can be given by,

\hat{n}\ =\ \dfrac{\vec{n}}{\left|\vec{n}\right|}

             =\ \dfrac{\dfrac{2x}{a^2}\hat{i}+\ \dfrac{2y}{b^2}\hat{j}+\ \dfrac{2z}{c^2}\hat{k}}{\sqrt{(\dfrac{2x}{a^2})^2+(\dfrac{2y}{b^2})^2+(\dfrac{2z}{c^2})^2}}

             

=\ \dfrac{\dfrac{x}{a^2}\hat{i}+\ \dfrac{y}{b^2}\hat{j}+\ \dfrac{z}{c^2}\hat{k}}{\sqrt{(\dfrac{x}{a^2})^2+(\dfrac{y}{b^2})^2+(\dfrac{z}{c^2})^2}}

Hence, the unit vector normal to each point of the given ellipsoid surface is

\hat{n}\ =\ \ \dfrac{\dfrac{x}{a^2}\hat{i}+\ \dfrac{y}{b^2}\hat{j}+\ \dfrac{z}{c^2}\hat{k}}{\sqrt{(\dfrac{x}{a^2})^2+(\dfrac{y}{b^2})^2+(\dfrac{z}{c^2})^2}}

3 0
3 years ago
You are going to mix a gallon bucket of window cleaner. The instructions direct you to mix 1 part cleaner to 3 parts water. How
Ira Lisetskai [31]
3 parts water
clean:water=1:3
1:3=xcleaner:1gallon
1/3=xcleaner/1gallon
times 3gallon both sides
1gallon=3xcleaner
divide both sides by 3
1/3 gallon=xcleaner

therfor you need 1/3 gallon of cleaner
7 0
3 years ago
Verify and show work<br><br> csc x - cos x • cot x = sin x
Vladimir79 [104]

Answer:   The answer is (d) ⇒ cscx = √3

Step-by-step explanation:

∵ sinx + (cotx)(cosx) = √3

∵ sinx + (cosx/sinx)(cosx) = √3

∴ sinx + cos²x/sinx = √3

∵ cos²x = 1 - sin²x

∴ sinx + (1 - sin²x)/sinx = √3 ⇒ make L.C.M

∴ (sin²x + 1 - sin²x)/sinx = √3

∴ 1/sinx = √3

∵ 1/sinx = cscx

∴ cscx = √3

5 0
2 years ago
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