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2 years ago

Calculate the area of the regular pentagon below:

Mathematics

2 answers:

KIM [24]2 years ago

5 0

The answer is 858.55 because A=145(5+25)a2

ch4aika [34]2 years ago

5 0

Answer:

888888555555555558888888888888888888888888888888888888888899....555 C lol fllow my tt tvdlover21 and helpingyou2shift

Step-by-step explanation:

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The current of a river is 3 miles per hour. A boat travels to a point 176 miles upstream and 176 miles back in 19 hours. What is

serious [3.7K]

Answer:

If I am understanding your question, the total upstream is 8 miles and another 8 miles downstream.

Let s = the speed of the boat in still water

d = rt

8 = 5(s + 3) downstream

8 = 5s + 15 equation 1

8 = 5(s - 3) upstream

8 = 5s - 15 Add equation 1

8 = 5s + 15

16 = 10s Divide both sides by 10.

s = 16/10 = 8/5 = 1.6 mph

4 0

2 years ago

Evaluate the integral by making an appropriate change of variables.

VARVARA [1.3K]

By inspecting the integrand, the "obvious" choice for substitution would be

u = y + x

v = y - x

Solving for x and y, we would have

x = (u - v)/2

y = (u + v)/2

in which case the Jacobian and its determinant are

$J=\begin{bmatrix}x_u&x_v\\y_u&y_v\end{bmatrix}=\dfrac12\begin{bmatrix}1&-1\\1&1\end{bmatrix}\implies|\det J|=\left|\dfrac12\right|=\dfrac12$

The trapezoid R has two of its edges on the lines x + y = 8 and x + y = 9, so right away, we have 8 ≤ u ≤ 9.

Then for v, we observe that when x = 0 (the lowest edge of R), v = y ; similarly, when y = 0 (the leftmost edge of R), v = -x. So

-x ≤ v ≤ y

-(u - v)/2 ≤ v ≤ (u + v)/2

-u + v ≤ 2v ≤ u + v

-u ≤ v ≤ u

So, the integral becomes

$\displaystyle\iint_R5\cos\left(7\frac{y-x}{y+x}\right)\,\mathrm dA=\int_8^9\int_{-u}^u\frac52\cos\left(\frac{7v}u\right)\,\mathrm dv\,\mathrm du$

$=\displaystyle\frac52\int_8^9\frac u7(\sin7-\sin(-7))\,\mathrm du$

$=\displaystyle\frac57\sin7\int_8^9u\,\mathrm du$

$=\displaystyle\frac5{14}\sin7(9^2-8^2)=\boxed{\frac{85}{14}\sin7}$

4 0

2 years ago

Kelvin finished $\frac{2}{3}$ 2 3 of his test in a $\frac{1}{2}$ 1 2 hour. Express this rate in hours per test.

svet-max [94.6K]

Complete Question

Kelvin finished 2/3 of his test in a 1/2 hour. Express this rate in hours per test.

Answer:

3/4 hours per test

Step-by-step explanation:

2/3 of his test = 1/2 hour

This rate in hours per test is calculated as:

x = 1/2 /2/3

x = 1/2 hour ÷ 2/3 test

x = 1/2 × 3/2

x = 3/4 hours per test

This rate in hours per test is given as 3/4 hours per test

4 0

2 years ago

Please help me not hard please

IrinaVladis [17]

Answer:

I think it's A

Step-by-step explanation:

8 0

3 years ago

a figure was rotated around a vertical line segment resulting in the object below. which of the figues was rotated

oksano4ka [1.4K]

Answer:

Step-by-step explanation:

7 0

3 years ago