Explanation:
The key to area in polar coordinates is the formula for the area of a sector:
a = (1/2)r²θ
Then a differential of area* can be written as ...
da = (1/2)r²·dθ
Filling in the given function for r, we have ...
da = (1/2)(4cos(3θ))²·dθ = 8cos(3θ)²·dθ
The integral will have limits corresponding to the range of values of θ for one loop of the graph: -π/6 to π/6. So, the area is ...

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* As with other approaches to finding area (horizontal or vertical slice, for example), we assume that the differential element dθ is sufficiently small that we need not concern ourselves with the fact that r is a function of θ.
Answer:
8
Step-by-step explanation:
To solve this problem, we need to find the area of the pen, then divide that by the area required by each dog.
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The relationship between circumference and radius is ...
C = 2πr
Solving for r gives ...
r = C/(2π)
The relationship between radius and area of a circle is ...
A = πr²
Substituting for r from above gives ...
A = π(C/(2π))² = C²/(4π)
Filling in the given numbers, we find the area of the pen to be ...
A = (78.5 ft)²/(4·3.14) = 490.625 ft²
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Dividing the pen area by the area per dog gives the number of dogs the pen can hold:
(490.625 ft²)/(60 ft²/dog) ≈ 8.18 dogs
The pen can safely keep 8 dogs.
Answer:
A non-equilateral rhombus.
Step-by-step explanation:
We can solve this graphically.
We start with square:
ABCD
with:
A = (11, - 7)
B = (9, - 4)
C = (11, - 1)
D = (13, - 4)
Only with the vertices, we can see that ABCD is equilateral, as the length of each side is:
AB = √( (11 - 9)^2 + (-7 -(-4))^2) = √( (2)^2 + (3)^2) = √(4 + 9) = √13
BC = √( (11 - 9)^2 + (-1 -(-4))^2) = √13
CD = √( (11 - 13)^2 + (-1 -(-4))^2) = √13
DA = √( (11 - 13)^2 + (-7 -(-4))^2) = √13
And we change C by C' = (11, 1)
In the image you can see the 5 points and the figure that they make:
The figure ABCD is a rhombus, and ABC'D is also a rhombus, the only difference between the figures is that ABCD is equilateral while ABC'D is not equilateral.
Answer:
2.5 mg
Step-by-step explanation:
.5 x 5 = 2.5