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Tju [1.3M]
3 years ago
14

How do you find the radius of a cylinder when you only know the surface area?

Mathematics
1 answer:
Paha777 [63]3 years ago
7 0

The surface area of a cylinder with circular bases of radius <em>r</em> and height <em>h</em> is equal to the sum of the areas of the two circular faces and the area of the rectangular lateral surface:

<em>A</em> = 2π<em>r</em>² + 2π<em>rh</em>

If you know the height <em>h</em>, then you can solve the quadratic equation for <em>r</em>.

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Use a half-angle identity to find the exact value
Tatiana [17]

Given:

\cos 15^{\circ}

To find:

The exact value of cos 15°.

Solution:

$\cos 15^{\circ}=\cos\frac{ 30^{\circ}}{2}

Using half-angle identity:

$\cos \left(\frac{x}{2}\right)=\sqrt{\frac{1+\cos (x)}{2}}

$\cos \frac{30^{\circ}}{2}=\sqrt{\frac{1+\cos \left(30^{\circ}\right)}{2}}

Using the trigonometric identity: \cos \left(30^{\circ}\right)=\frac{\sqrt{3}}{2}

            $=\sqrt{\frac{1+\frac{\sqrt{3}}{2}}{2}}

Let us first solve the fraction in the numerator.

            $=\sqrt{\frac{\frac{2+\sqrt{3}}{2}}{2}}

Using fraction rule: \frac{\frac{a}{b} }{c}=\frac{a}{b \cdot c}

            $=\sqrt{\frac {2+\sqrt{3}}{4}}

Apply radical rule: \sqrt[n]{\frac{a}{b}}=\frac{\sqrt[n]{a}}{\sqrt[n]{b}}

           $=\frac{\sqrt{2+\sqrt{3}}}{\sqrt{4}}

Using \sqrt{4} =2:

           $=\frac{\sqrt{2+\sqrt{3}}}{2}

$\cos 15^\circ=\frac{\sqrt{2+\sqrt{3}}}{2}

5 0
3 years ago
Can someone pls help me? :)
erastova [34]

Step-by-step explanation:

1 t=16/21

2.m=2

3.n=13/7

4.a=2

5.x=6/17

6.x=15

7.s=21/4

8. t=7/3

9. s=1

10. s=6/61

11. x=1/3

12. r=27/16

13. c=−1

14.m=9/5n

15. j=−117/58

8 0
3 years ago
Plane A is descending toward the local airport, and plane B is ascending from the same airport. Plane A is descending at a rate
Bas_tet [7]

Answer: 2 minutes

Step-by-step explanation:

Given the following :

Plane A's descent :

y = -2,500x + 14,000

Plane B's Ascent :

y = 4,000x + 1,000

where y = altitude x = minute

Time to be at the same altitude :

Being at the same altitude means ;

Plane A's descent = Plane B's Ascent

-2,500x + 14,000 = 4,000x + 1,000

-2500x - 4000x = 1000 - 14000

-6500x = - 13000

x = 13000 / 6500

x = 2

x = 2minutes.

5 0
3 years ago
Find the greatest number that divides451, 328 and 673 leaving 1, 4 and 1,respectively as remainders.
Vesna [10]

You're looking for the largest number <em>x</em> such that

<em>x</em> ≡ 1 (mod 451)

<em>x</em> ≡ 4 (mod 328)

<em>x</em> ≡ 1 (mod 673)

Recall that

<em>x</em> ≡ <em>a</em> (mod <em>m</em>)

<em>x</em> ≡ <em>b</em> (mod <em>n</em>)

is solvable only when <em>a</em> ≡ <em>b</em> (mod gcd(<em>m</em>, <em>n</em>)). But this is not the case here; with <em>m</em> = 451 and <em>n</em> = 328, we have gcd(<em>m</em>, <em>n</em>) = 41, and clearly

1 ≡ 4 (mod 41)

is not true.

So there is no such number.

4 0
3 years ago
The population of current statistics students has ages with mean muμ and standard deviation sigmaσ. samples of statistics studen
Aleonysh [2.5K]

What does the central limit theorem tell us about the distribution of those mean​ ages?

<span>A.    </span>Because n>30, the sampling dist of the mean ages can be approximated by a normal dist with a mean u and a SD o/sqrt 54,

Whenever n<span>>30 the central limit theory applies.</span>

6 0
3 years ago
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