12. What is the equation of the following parabola?

What is the length of the arc intercepted by an angle of 10 degrees on a circle with a radius of 10 meters?

soldier1979 [14.2K]

$\displaystyle\\
\texttt{Length of the arc }= 2\pi R\times \frac{10}{360} = \frac{2\pi \times 10}{36} = \frac{20\pi}{36} = \boxed{\frac{5\pi}{9}~m}$

3 0

2 years ago

If a/b < c/d with b > 0, d > 0, prove that a+c / b+d lies between the two fractions a/b and c/d .

Tems11 [23]

Divide through everything by b :

$\dfrac{a+c}{b+d} = \dfrac{\dfrac ab + \dfrac cb}{1 + \dfrac db}$

Since a/b < c/d, it follows that

$\dfrac{a+c}{b+d} < \dfrac{\dfrac cd+\dfrac cb}{1 + \dfrac db}$

Multiply through everything on the right side by b/d to get

$\dfrac{a+c}{b+d} < \dfrac{\dfrac{bc}{d^2}+\dfrac cd}{\dfrac bd+1} = \dfrac{\dfrac cd\left(\dfrac bd+1\right)}{\dfrac bd+1} = \dfrac cd$

and so (a + c)/(b + d) < c/d.

For the other side, you can do something similar and divide through everything by d :

$\dfrac{a+c}{b+d} = \dfrac{\dfrac ad + \dfrac cd}{\dfrac bd + 1}$

and a/b < c/d tells us that

$\dfrac{a+c}{b+d} > \dfrac{\dfrac ad + \dfrac ab}{\dfrac bd + 1}$

Then

$\dfrac{a+c}{b+d} > \dfrac{\dfrac ab + \dfrac{ad}{b^2}}{1 + \dfrac db} = \dfrac{\dfrac ab\left(1+\dfrac db\right)}{1 + \dfrac db} = \dfrac ab$

and so (a + c)/(b + d) > a/b.

Then together we get the desired inequality.

5 0

2 years ago

are any two regular polygons similar. The area of the smaller figure is about 390 cm^2. choose the best estimate of the area of

galben [10]

Answer:

The best estimate of the area of the larger figure is $693\ cm^{2}$

Step-by-step explanation:

step 1

Find the scale factor

we know that

If two figures are similar, then the ratio of its corresponding sides is equal to the scale factor

Let

z----> the scale factor

x-----> the corresponding side of the larger figure

y-----> the corresponding side of the smaller figure

so

$z=\frac{x}{y}$

we have

$x=12\ cm$

$y=9\ cm$

substitute

$z=\frac{12}{9}=\frac{4}{3}$ -----> the scale factor

step 2

Find the area of the larger figure

we know that

If two figures are similar, then the ratio of its areas is equal to the scale factor squared

Let

z----> the scale factor

x-----> the area of the larger figure

y-----> the area of the smaller figure

so

$z^{2}=\frac{x}{y}$

we have

$z=\frac{4}{3}$

$y=390\ cm^{2}$

substitute and solve for x

$(\frac{4}{3})^{2}=\frac{x}{390}$

$(\frac{16}{9})=\frac{x}{390}$

$x=390*16/9=693.33\ cm^{2}$

4 0

2 years ago

Which polynomial correctly combines the like terms and expresses the given polynomial in standard form? 8mn5 – 2m6 + 5m2n4 – m3n

photoshop1234 [79]

So it's multiple choice?
whichever looks most like this is the answer:
30mn+6n-36m

8 0

2 years ago

Read 2 more answers

It is called a _____ when each person in the population has an equal chance of being selected.random sampleself-selected sampleb

Georgia [21]

It's a random sample

5 0

2 years ago