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yaroslaw [1]
3 years ago
8

Given that Triangle ABC such thata=8cm, b=7cm and c=9cmtem and c= 9cm find Cos B​

Mathematics
1 answer:
charle [14.2K]3 years ago
4 0

Answer:

We use cosine rule also called cosine law which states

c^2=a^2+b^2-2abcosC

given

a=8cm, b=7cm, c=9cm cos C?

9^2=8^+7^2-2*8*7 cos C

expand

81=64+49-112 cos C

like terms together

81-113=-112 cos C

-32=-112cos C

multiply both sides by -1

32=112cos C

divide both sides by 112

32/112=cos C

cosC=0.2857

find cos inverse of 0.2857

angle C= 73.40

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Paul [167]

Answer: True

Solution:

Rearrange the equation to the LHS:

[x^2 + 8x + 16] · [x^2 – 8x + 16] - (x^2 – 16)^2 = 0

Factoring  x^2+8x+16

x^2 - 4x - 4x - 16

= (x-4)  •  (x-4)

= = (x+4)2

So now we have an equation

(x + 4)^2 • (x - 4)^2 -  (x^2 - 16)^2  = 0

Step 2: Evaluate the following:

(x+4)2   =    x^2+8x+16

(x-4)2   =    x^2-8x+16  

(x^2-16)2   =    x^4-32x^2+256

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0 = 0

Hence True

3 0
3 years ago
Which equation shows the relationship between x & y?
algol13
I believe it is the first one but I might be wrong.
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3 years ago
20 POINTS AND BRAINLIEST!!! You are given an n×n board, where n is an even integer and 2≤n≤30. For how many such boards is it po
Bess [88]

Answer:

  5

Step-by-step explanation:

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If the tiles are colored in an alternating pattern, tiles must have 3 of one color and 1 of the alternate color. Hence the total number of tiles used to cover a board must be even (so the numbers of each color match). Then the board dimension must be divisible by 4.

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3 years ago
50 points for answer
jarptica [38.1K]

Answer:

Step-by-step explanation:

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5 0
3 years ago
Read 2 more answers
You have some money in your wallet. You don't know the exact amount, but you think you have 60 dollars give or take 15 dollars.
Karolina [17]

Answer:

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The biggest amount is 125 dollars

Step-by-step explanation:

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Defining the function.

Let x be the exact amount of money in my pocket, we can define the equation

And we know that the difference between the exact amount of money with 100 dollars must be either 25 dollars more than what we estimated, or 25 dollars less than the estimation.  So we can write:

We have a difference inside an absolute value, since we know the difference must be either +25 or -25.

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Solving for x give us

So the least amount of money in my pocket is 75 dollars and the biggest amount is 125 dollars.

6 0
2 years ago
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