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kramer
4 years ago
13

Find the exact value of cos 157.5°.

Mathematics
1 answer:
Nonamiya [84]4 years ago
3 0
Cos 157.5º=-cos (180º-157.5º)=-cos 22.5=-cos(45/2)

cos Ф/2=⁺₋√((1+cosФ)/2).

In this case 157.5º is in the second quadrant, therefore we use the following equation:
cos Ф/2=-√((1+cosФ)/2).          (we will have a negative number)

cos 157.5º=-cos (45/2)=-√((1+cos 45º)/2)
=-√((1+√2/2)/2)
=-√((2+√2)/4)
=-√(2+√2) / 2   (≈-0.92387...)

Answer: cos 157.5º= -√(2+√2) / 2

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PtichkaEL [24]
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Based on that rule, we can say
d+100 = 180
d+100-100 = 180-100
d = 80

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What is the rate of change from 2<br> gallons to 4 gallons? Pls I need help!!
Tema [17]

Answer:

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Step-by-step explanation:

4 0
3 years ago
For whole numbers between 1 and 1001, inclusive, let m be the sum of odd numbers and n be the sum of even numbers. What is the v
Svetradugi [14.3K]

Answer:

m - n = 501

Step-by-step explanation:

Remark

The first thing you have to do is find the number of odd and even numbers. This is where you have to be careful because there is a danger of being out by one.

equation

l = a + (n - 1)*d

Solution even

l = 1000

a = 2

d = 2

1000 = 2 + (n - 1)*2

998/2 = (n - 1) * 2 / 2

499 =  n - 1

n = 500

Solution odd

l = 1001

a = 1

d = 2

1001 = 1 + (n - 1)*2

1000 =  (n - 1)*2

1000/2 =  (n - 1)2/2

500 =  n - 1

501 = n

Sum Even of even numbers from 1 to 1001

Givens

a = 2

n = 500

l = 1000

Equation

Sum = (a + l ) * n / 2

Solution

Sum = (2 + 1000)*500/2

Sum = 1002 * 250

Sum = 250500

Sum of Odd numbers from 1 to 1001

a = 1

l = 1001

n = 501

Equation

sum = (a + l)*n/2

sum = (1 + 1001) * 501

sum = (1002)*501 / 2

Sum =  251001

Answer

m - n = 251001 - 250500 = 501

6 0
3 years ago
At the store a cell phone cost 1.1 times as much as it sells online. If it cost $888.98 online, how much more does it cost from
Airida [17]

Given:

At the store a cell phone cost 1.1 times as much as it sells online.

The cost of it is $888.98 online.

To find:

How much more does it cost from the store?

Solution:

It is given that,

Cost of a cell phone online = $888.98

At the store a cell phone cost 1.1 times as much as it sells online. So, cost of the cell phone at store is

1.1\times (888.98)=977.878&#10;

The cost of cell phone at store is $977.878 .

The difference between the cost of cell phone at store and online is

\$977.878&#10;-\$888.98=\$88.898

Therefore, the cell phone cost is $88.898 much more at the store.

8 0
3 years ago
If f(x) = -2x + 5, find x when f(x)=17..
VARVARA [1.3K]

Answer:

x= -6

Step-by-step explanation:

17=-2x+5

17-5=-2x+5-5

12= -2x then divided both side by -2

-6=x

4 0
3 years ago
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