1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Sergio [31]
2 years ago
9

I'm having trouble with #2. I've got it down to the part where it would be the integral of 5cos^3(pheta)/sin(pheta). I'm not sur

e where to go from there. U-sub won't work and neither will taking out a tan(pheta). Please help. Thanks

Mathematics
2 answers:
jeka57 [31]2 years ago
5 0


Setting , you have . Then the integral becomes






Now,  in general. But since we want our substitution  to be invertible, we are tacitly assuming that we're working over a restricted domain. In particular, this means , which implies that , or equivalently that . Over this domain, , so .

Long story short, this allows us to go from



to




Computing the remaining integral isn't difficult. Expand the numerator with the Pythagorean identity to get



Then integrate term-by-term to get




Now undo the substitution to get the antiderivative back in terms of .



and using basic trigonometric properties (e.g. Pythagorean theorem) this reduces to
Butoxors [25]2 years ago
4 0
\displaystyle\int\frac{\sqrt{25-x^2}}x\,\mathrm dx

Setting x=5\sin\theta, you have \mathrm dx=5\cos\theta\,\mathrm d\theta. Then the integral becomes

\displaystyle\int\frac{\sqrt{25-(5\sin\theta)^2}}{5\sin\theta}5\cos\theta\,\mathrm d\theta
\displaystyle\int\sqrt{25-25\sin^2\theta}\dfrac{\cos\theta}{\sin\theta}\,\mathrm d\theta
\displaystyle5\int\sqrt{1-\sin^2\theta}\dfrac{\cos\theta}{\sin\theta}\,\mathrm d\theta
\displaystyle5\int\sqrt{\cos^2\theta}\dfrac{\cos\theta}{\sin\theta}\,\mathrm d\theta

Now, \sqrt{x^2}=|x| in general. But since we want our substitution x=5\sin\theta to be invertible, we are tacitly assuming that we're working over a restricted domain. In particular, this means \theta=\sin^{-1}\dfrac x5, which implies that \left|\dfrac x5\right|\le1, or equivalently that |\theta|\le\dfrac\pi2. Over this domain, \cos\theta\ge0, so \sqrt{\cos^2\theta}=|\cos\theta|=\cos\theta.

Long story short, this allows us to go from

\displaystyle5\int\sqrt{\cos^2\theta}\dfrac{\cos\theta}{\sin\theta}\,\mathrm d\theta

to

\displaystyle5\int\cos\theta\dfrac{\cos\theta}{\sin\theta}\,\mathrm d\theta
\displaystyle5\int\dfrac{\cos^2\theta}{\sin\theta}\,\mathrm d\theta

Computing the remaining integral isn't difficult. Expand the numerator with the Pythagorean identity to get

\dfrac{\cos^2\theta}{\sin\theta}=\dfrac{1-\sin^2\theta}{\sin\theta}=\csc\theta-\sin\theta

Then integrate term-by-term to get

\displaystyle5\left(\int\csc\theta\,\mathrm d\theta-\int\sin\theta\,\mathrm d\theta\right)
=-5\ln|\csc\theta+\cot\theta|+\cos\theta+C

Now undo the substitution to get the antiderivative back in terms of x.

=-5\ln\left|\csc\left(\sin^{-1}\dfrac x5\right)+\cot\left(\sin^{-1}\dfrac x5\right)\right|+\cos\left(\sin^{-1}\dfrac x5\right)+C

and using basic trigonometric properties (e.g. Pythagorean theorem) this reduces to

=-5\ln\left|\dfrac{5+\sqrt{25-x^2}}x\right|+\sqrt{25-x^2}+C
You might be interested in
You have $3.70 in dimes and quarters. You have 5 more
anygoal [31]

Answer:

Step-by-step explanation:

10x + 25y = 370

y = x + 5

10x+25(x+5)=370

10x+25x+125=370

35x=370-125

x=245/35

x=7 which is the number of dimes

x+7= 7+5= 12 which is the number of quarters

So you have 12 quarters. That means you have 7 dimes.

8 0
2 years ago
Which is a possible turning point for the continuous function f(x)?
babymother [125]

Answer:

We are given coordinates of a continuous function f(x)

(–2, 0)

(0, –2)

(2, –1)

(4, 0).

We need to find the possible turning point for the continuous function.

Note: Turning point is a point on the graph where slope of the curve changes from negative to positive or positive to negative.

A turning point is always lowest or highest point of the curve (where bump of the graph seen).

For the given coordinates we can see that  (–2, 0) and (4, 0) coordinates are in a same line, that is on the x-axis.

But the coordinate  (0, –2) is the lowest point on the graph.

Therefore, (0, –2) is the turning point for the continuous function given.

hoped this was helpful!

5 0
2 years ago
I need help with number 8
murzikaleks [220]
Since we know what he earns hourly, and his sales, we can figure out his full gross pay for the week.
As so:

We can set up an equation like this:
<em>h</em> = hours
<em>s</em> = sales
9.60h + 5%s

Now, we substitute.
9.60(35) + 5%(230)

Next, solve.
336.00 + 11.50
$347.50

$347.50 was Glen's gross pay for the week.

Hope I could help! If my math is wrong, or I did not provide the answer you were looking for, let me know! However, if I did well, please consider marking as <em>Brainliest!
</em>Have a good one!

8 0
3 years ago
Read 2 more answers
A gas has a volume of 5.0 L at a pressure of 50kPa. What happens to the volume when then the pressure is increased 125kPa. The t
Olegator [25]

9514 1404 393

Answer:

  volume goes to 2.0 L

Step-by-step explanation:

At constant temperature, volume and pressure are inversely related. Increasing the pressure by a factor of 125/50 = 2.5 will cause the volume to be reduced by that factor.

  volume = 5.0L / 2.5

  volume = 2.0 L

7 0
3 years ago
The table below shows the ages of employees over 50 at a company and the amount of money they have in their retirement accounts.
sp2606 [1]

Answer:

c

Step-by-step explanation:

plot your graph and then you will see there is no line which shows there is a correlation. they're too scattered

4 0
3 years ago
Other questions:
  • Subtract -b + 3 from -11b - 4<br><br> 10b - 7<br> -10b -7<br> 10b + 7<br> -12b - 1
    5·1 answer
  • The list shows the number of stories in the 11 tallest buildings
    10·1 answer
  • How can you solve an equation with a variable on both sides
    10·2 answers
  • Help with 4-9 please
    8·1 answer
  • Please help!! What is the value of the sum? Drag and drop the answer into The box to match the sum with its value. 5/6 + (-1/2).
    6·1 answer
  • When Marcus weighed the watermelon in his garden a week ago, it weighed 2.8 pounds. Yesterday, the watermelon weighed 4.67 pound
    11·2 answers
  • Find the differential equation of this function and indicate the order y = e^3x (acos3x +bsin3x)​
    8·1 answer
  • I need helpppppppppp
    14·2 answers
  • HELP ILL GIVE BRAINLIEST AND THANKS
    13·1 answer
  • Can some one pls help
    14·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!