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kompoz [17]
2 years ago
14

What is the exact value of cos (7pi/8)

Mathematics
1 answer:
Mrac [35]2 years ago
6 0

Answer:

The bottom one ....see below

Step-by-step explanation:

Using reference angle of pi/8   and half angle trig identity:

cos ( angle/2) = -sqrt  (1 + cos (angle) /2)

cos ( pi/4  / 2) = - sqrt (1+ cos ( pi/4)/2)

  <u> cos (pi/8)</u>      = -    sqrt (1 + sqrt (2) / 2)

                 = - sqrt (1 + sqrt 2) / sqrt 2     rationalize the denominator

                    = - sqrt ( sqrt 2 + 2) / 2

re arrange to

          - sqrt ( 2 + sqrt2)  / 2        the fourth answer  

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The sum of two integers is 121. The larger integer is 7 more than twice the smaller integer. Find the two integers.
iren [92.7K]
X + (2x + 7) = 121 : Write the expression.
3x + 7 = 121 : Combine like terms.
3x + 7 - 7 = 121 - 7 : Isolate x.
3x = 114 : Combined like terms.
3x / 3 = 114 / 3 : Find the value of x.
x = 38 : This is the smaller integer.
(2x + 7) = (2(38) + 7) = 76 + 7 = 83. : Find the value of the larger number by plugging in the value of x to the larger number's quantity.
The larger number is 83, and the smaller number is 38.
5 0
3 years ago
Show work please i will give brailiest show work pls
Crank
1. 2-1+5x4x11
5x4=20
2-1+20x11
20x11=220
2-1+220
2-1=1
1+220=221

2. 14/2-1+3
14/2=7
7-1+3
7-1=6
6+3=9

3. 3x8x2-42+5
3x8=24
24x2-42+5
24x2=48
48-42+5
48-42=6
6+5=11
5 0
3 years ago
What is 823,563 rounded to the nearest ten thousand? (1 poin<br> 820.000<br> 325.000<br> 330.000
valentina_108 [34]

Answer: 820,000

823,563 rounded to the nearest ten thousand is 820,000

3 0
3 years ago
The function y = x + 7 is graphed in the coordinate plane. Which point will NOT be on the line?
Anika [276]

The correct answer is

B) (2,14)

8 0
3 years ago
Find the reciprocal of the expression. 10b/2b + 8
Alexus [3.1K]
Comment
I think you need brackets to clarify what you mean. I think it should be written as 
10b/(2b + 8) 

If that is the case the reciprocal is

(2b + 8)/10b You just turn everything up side down. There are technical ways of doing this, but the easiest way is just to do what I just did. 

Put the numerator in  the denominator,
Put the denominator in the numerator.

You could simplify this a bit.
2b/10b + 8/10b
which reduces further.

1/5 + 4/5b 
Just to make sure you understand where that b is, I will do this in

Latex.\frac{2b + 8}{10b} =  \frac{2b}{10b} +  \frac{8}{10b} =  \frac{2}{10} + \frac{4}{5b} =  \frac{1}{5} +  \frac{4}{5b}

Alternate answer
If you do mean what your wrote then the reciprocal is 2b / 10b + 8 which is 1/5 + 8 = 8 + 0.2 = 8.2 

The 8 has nothing to do with the reciprocal under these conditions.

The answer
I have given you all the choices I can think of without going into decimals. If you have choices, please list them under the comments.
6 0
3 years ago
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