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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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Answer:

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Step-by-step explanation:

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3 years ago
What’s the domain and range for these two?
user100 [1]

Step-by-step explanation:

1) the domain is from -3 to 5 D [-3,5]

the range is from -5 to -2. R [-5,-2]

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2 years ago
Which equations represent functions? ​
Margaret [11]

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Step-by-step explanation:

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3 0
2 years ago
6. The perimeter of a parallelogram is 100 meters. The width of the parallelogram is 4 meters less than its length. Find the len
Ierofanga [76]

Answer:

x = 23, and y = 27.

Step-by-step explanation:

Lets say,

x = width

y = length

this means,

x(2) + y(2) = 100

It also says that the width is 4 meters less than the length.

if we put that into equation form it would look like this,

y - 4 = x

using these 2 equations, we can use the subustusion method to find the x.

x(2) + y(2) = 100

turns in to this :

step 1.     (y - 4) (2) + y(2) = 100 - given

step 2.      2y -8 + 2y = 100 -  distribute

step 3.      4y -8 = 100 - Combine like terms

step 4.       4y  = 108 - Get rid of the 8

step 5        4y/4  = 108 /4 - divide

step 6 .          y = 27

So if y is 27, then

x(2)  +  27(2) = 100

x(2) + 54 = 100

100 - 54 = 46, so x(2) is 46, but to get x, we need to divide 46 by 2, since x multiplied by 2 equals 46.

46  / 2 = 23 = x

so x = 23, and y = 27.

and the rule that y - 4 = x still applies, since 27 - 4 = 23.

I hope this wasn't confusing! It did take a long time tho.

5 0
3 years ago
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