can
5. (a) Find the expansion of cos(x + y) and cos(x – y). Show that cos(x + y) cos(x - y)
be written as cos x - sin?
y.
(5 marks)
(b) Hence, from part (a) and without using the calculator, find the value of
cos(75°) cos (15°), where x and y are special angles.
(5 marks)

Answers

Answer 1

Answer:

The identity is: cos(x+y)cos(x-y) = cos^2(x) - sin^2(y).  Answer to part (b) is 1/4

Step-by-step explanation:

cos(x+y) = cos(x) cos(y) - sin(x)sin(y)

cos(x-y) = cos(x)cos(y) + sin(x)sin(y)

For convenience, let A = cos(x) cos(y), and B = sin(x) sin(y).

Thus,

cos(x+y) = A - B

cos(x-y) = A + B, and

cos(x+y) cos(x-y) = (A-B)(A+B) = A^2 - B^2 = cos^2(x) cos^2(y) - sin^2(x)sin^2(y) = (1 - sin^2(x))(1 - sin^2(y)) - sin^2(x) sin^2(y) =

1 - sin^2(x) - sin^2(y) + sin^2(x) sin^2(y) - sin^2(x) sin^2(y) =

1 - sin^2(x) - sin^2(y) =

cos^2(x) - sin^2(y)

(b) Let x=45, and y=30, so we have that

cos(75)cos(15) = cos(45+30) cos(45-30) =

cos^2(45) - sin^2(30) =

(sqrt(2)/2)^2 - (1/2)^2 =

2/4 - 1/4 =

1/4


Related Questions

Hey , can you help please and thanks

Answers

Answer:

13/4 gallons per bucket or (as a mixed number) 3 and 1/4

Step-by-step explanation:

a gallon is made up of 4 quarts

so 13 qt/bucket* 1 gal/4 qts = 13/4 gal/bucket  This label is because, since the quart labels are on opposite sides of the slash or division line this means we can cancel them which is why I multiplied it by 1 gal/4 gts instead of 4 qts/1 gal because even though both are true, one would cancel and one wouldn't.


Translate the sentence into an inequality.

The sum of a number times 9 and 16 is at least 22.

Use the variable c for the unknown number.


Answers

I am thinking it should be c•9•16>_ 22 (greater than or equal to 22)

Please help! What values of x make the matrix M have an inverse?

Answers

Answer:

I'm not sure I'm only in middle school, but I'll put what I know.

Step-by-step explanation:

Step 1: Calculate the minor for the given matrix.

Step 2: Turn the obtained matrix into the matrix of cofactors.

Step 3: Then, the adjugate, and.

Step 4: Multiply that by reciprocal of determinant.

Place the numbers in order from greatest to least.

Answers

Answer:

C

Step-by-step explanation:

0.528 is the smallest number and C is the only one that starts with it

Which of the following is an infinite set?
A)The Set of numbers between 4 and 5
B){1,2,3,…………..1000}
C)The Set of positive integers less than 100
D)None of these

Answers

Answer:

The number of elements in a finite set A is denoted by n(A). Examples: If A is the set of positive integers less than 12 then. A = {1, 2, 3, 4, 5, 6, 7, 8, ...

13, 69, 89, 25, 55, 20, 99, 75, 42, 18, 66, 88, 89, 79, 75, 65, 25, 99, 66, 78. Order from least to greatest

Answers

13, 18, 20, 25, 25, 42, 55, 65, 66, 66, 69, 75, 75, 78, 79, 88, 89, 95, 99

Need helppppppppppppppppppppp

Answers

Answer: x = 45cm

Step-by-step explanation: 27/18 = 1.5

1.5 is your scale factor now do 30 x 1.5 and you will get 45

COORDINATE GEOMETRY Find the perimeter and area of each figure with the given vertices. 20. D(-2,-2), E(-2, 3), and F(2, -1)​

Answers

Step-by-step explanation:

Find the sides and perimeter:

DE = 3 - (-2) = 5EF = [tex]\sqrt{(2+2)^2+(-1+2)^2} =\sqrt{17}[/tex] ≈ 4.1DF = [tex]\sqrt{(2+2)^2+(3+2)^2} =\sqrt{41}[/tex] ≈ 6.4

Perimeter:

P = 5 + 4.1 + 6.4 = 15.5 units

Find the area using shoelace formula:

A = 1/2|(x₁y₂ + x₂y₃ + x₃y₁) - (y₁x₂ + y₂x₃ + y₃x₁)|=1/2|(-2*3 + -2* -1 + 2* -2) - (-2* -2 + 3*2 - 1* -2)|=1/2|(-6 + 2 - 4) - (4 + 6 + 2)| =1/2|-8 - 12| =1/2(20) = 10 units²

A fish store can place 5 fish in each fish bowl. If there are 263 fish to place, how many fish bowls are needed for all 263 fish?

Answers

Answer:

Step-by-step explanation:

1 bowl holds 5 fish

x bowls hold 263 fish

1/x = 5/263                      Cross multiply

5x = 263                         Divide by 5

5x/5 = 263/5

x = 52.6

So you actually need 53 fishbowls. One of them holds only 3 fish

I am a quadrilateral with all four sides congruent. My all interior angles are congruent. The sum of my interior angles is 360°. My area is equal to the square of my length. I am? ​

Answers

Answer:
Square

Reasoning:
All sides are congruent meaning equal in length. If you add all angles 90+90+90+90=360°

Hope this helps! <3
the answer is you are is a square

Suppose that an individual has a body fat percentage of 17.6% and weighs 139 pounds. how many pounds of her weight is made up of fat? round your answer to the nearest tenth.

Answers

Answer:

24.5 pounds

Step-by-step explanation:

0.176*139= 24.5

At a hockey game, a vender sold a combined total of 127 sodas and hot dogs. The number of sodas sold was 43 more than the number of hot dogs sold. Find the number of sodas sold and the number of hot dogs sold. Number of sodas sold: ​

Answers

Answer:

85 sodas

Step-by-step explanation:

Total sold was 127

The number of sodas was 43 + the number of hotdogs

Let x represent hotdogs:

x + (43 + x) = 127                (The 43 + x is the number of sodas sold.)

2x + 43 = 127

2x = 84

x = 42

42 hotdogs were sold., Since sodas are 42 + 43, 85 sodas were sold

-Chetan K

Consider the arithmetic sequence with a first term of 11 and sixth term of 21. What is the
sum of these first six terms?

A: 192
B: 52
C: 142
D: 96

Answers

Answer:

96Consider the arithmetic sequence with a first term of 11 and sixth term of 21. What is the

sum of these first six terms?

The required sum of the first 6th term of an arithmetic progression is 96. Option D is correct.

Given that,
Consider the arithmetic sequence with the first term of 11 and the sixth term of 21. To determine the sum of these first six terms.

What is arithmetic progression?

Arithmetic progression is the series of numbers that have common differences between adjacent values

What is geometric progression?

Geometric progression is a sequence of series whose ratio with adjacent values remains the same.


Here,
First term a = 11
6th term = a + 5d
21 = 11 + 5d
5d = 10
d = 2
Now,
sum of the six terms, = 6 / 2{11 + 21}
                                   = 3 (32)
                                   = 96

Thus, the required sum of the first 6th term of an arithmetic progression is 96. Option D is correct.

Learn more about arithmetic progression here: https://brainly.com/question/20334860

#SPJ2

Suppose that $3000 is placed in a savings account at an annual rate of 3.6%, compounded monthly. Assuming that no withdrawals are made, how long will it take for the account to grow to $4500? Do not round any intermediate computations, and round your answer to the nearest hundredth.

Answers

Using compound interest, it is found that it will take 11.28 years for the the account to grow to $4500.

The compound interest formula is given by:

[tex]A(t) = P(1 + \frac{r}{n})^{nt}[/tex]

A(t) is the amount of money after t years.

P is the principal(the initial sum of money).

r is the interest rate(as a decimal value).

n is the number of times that interest is compounded per year.

t is the time in years for which the money is invested or borrowed.

In this problem:

$3000 is placed in the account, thus [tex]P = 3000[/tex].Interest rate of 3.6%, thus [tex]r = 0.036[/tex].Monthly compounding, thus [tex]n = 12[/tex].

We have to solve for t when [tex]A(t) = 4500[/tex], thus:

[tex]A(t) = P(1 + \frac{r}{n})^{nt}[/tex]

[tex]4500 = 3000(1 + \frac{0.036}{12})^{12t}[/tex]

[tex](1.003)^{12t} = 1.5[/tex]

[tex]\log{(1.003)^{12t}} = \log{1.5}[/tex]

[tex]12t\log{1.003} = \log{1.5}[/tex]

[tex]t = \frac{\log{1.5}}{12\log{1.003}}[/tex]

[tex]t = 11.28[/tex]

It will take 11.28 years for the the account to grow to $4500.

A similar problem is given at https://brainly.com/question/24507395

need help with What is F(x)=a*b^x please explain the steps

Answers

9514 1404 393

Answer:

33(1,6)2f(x) = 3·2^x

Step-by-step explanation:

The blanks you're to fill in explain the steps.

The y-intercept is the value of the function when x=0. It is where the graph crosses the y-axis.

  f(0) = a·b^0 = a·1 = a

Reading the y-intercept from the graph, we see ...

  The y-intercept is 3. The a-value of the function is 3.

__

The point when x=1 is ...

  f(1) = a·b^1 = 3b

Reading the value from the graph, we find the point to be (1, 6). This means ...

  3b = 6

  b = 2 . . . . . . . divide both sides by 3

 The point when x=1 is (1, 6). The b-value of the function is 2.

 The equation of the function is f(x) = 3·2^x.

4. (4)5 =
a. 12
b. 13
c. 14
d. 15

Answers

[tex]▪▪▪▪▪▪▪▪▪▪▪▪▪  {\huge\mathfrak{Answer}}▪▪▪▪▪▪▪▪▪▪▪▪▪▪[/tex]

[tex](4 {}^{3} ) {}^{5} [/tex]

[tex](4{}^{3 \times 5} )[/tex]

[tex]4 {}^{15} [/tex]

therefore, the Correct choice is d) 15

In this case, D (15) is the correct answer

4^15

What is 6% of 90? Helpp​

Answers

Answer:

54

Step-by-step explanation:

6/100 = x/90

6×90=540

540/100=54

= Homework: Lsn 30- Review For Midterm #1 QL 2. A wheel made 200 revolutions at 275 revolutions per minute. How many minutes did it rotate? 7 63 How many minutes did the wheel rotate? 7 191 (Type a whole number, proper fraction, or mixed number)​

Answers

9514 1404 393

Answer:

  8/11 minutes

Step-by-step explanation:

To find the time, divide the quantity by the rate:

  (200 rev)/(275 rev/min) = (200/275) min = 8/11 min

The wheel rotated for 8/11 minutes.

The total weight limit for a truck is 100,000 lb. The truck weighs 36,000 lb empty. What is the most that the truck's load can weigh?​

Answers

Answer: 64,000} lbs

Step-by-step explanation: hope it helps ! <3!

Find the quotient of 2 2 3 and 3 1 2 Give your answer as a fraction in its simplest form.

Answers

The correct answer is:  " [tex]\frac{16}{21}[/tex] " .

_______

Step-by-step explanation:

" [tex]2\frac{2}{3}[/tex]  ÷ [tex]3\frac{1}{2}[/tex] "  =  

               " [tex]\frac{(2\frac{2}{3})}{(3\frac{1}{2})}[/tex]   "  ;

_______

" [tex]2\frac{2}{3} = \frac{[(3*2)+2]}{3} = \frac{(6+2)}{3} = \frac{8}{3}[/tex]  " .

_______

" [tex]3\frac{1}{2} = \frac{[(2*3)+1]}{2} = \frac{(6+1)}{2} = \frac{7}{2}[/tex]  " .

_______

→  "  [tex]\frac{(2\frac{2}{3})}{(3\frac{1}{2})}[/tex]  " ;

          [tex]} = \frac{8}{3}[/tex] ÷ [tex]\frac{7}{2}[/tex]  ;

Note that "dividing by a value"  results in the same value as "multiplying by the reciprocal of that value" ;

  The reciprocal of:  " [tex]\frac{7}{2}[/tex] " ;  is:  " [tex]\frac{2}{7}[/tex] " ;

_______

         [tex]= \frac{8}{3} *\frac{2}{7}= \frac{(8*2)}{(3*7)} = \frac{16}{21}[/tex] ;  which cannot be further reduced as a fraction.

_______

The correct answer is:  " [tex]\frac{16}{21}[/tex] " .

_______

Hope this is helpful!

 Best wishes to you!

_______

If l || m, find the value of each missing variable(s).

Answers

Answer:

12

Step-by-step explanation:

13x-21=5x+75

8x=96

x=96/8=12

Answer:

x=12

Step-by-step explanation:

Since the 2 lines are parallel we can use the rules of transversals. These 2 angels are alternate side interior. This means that they are congruent and have the same measurement. Because they have the same measurement, we can set them equal to each other and solve for x.

First, set the expressions equal to each other

13x-21 = 5x+75

Next, add 21 to both sides

13x = 5x+96

Then, subtract 5x from both sides

8x = 96

Finally, divide both sides by 8

x=12

help I'm going to die here I have a 23% in this class​

Answers

Answer:

0.0026

I don't know how to add the work here

please help meeeeeeeee

Answers

Answer:

3.32 dollars/gallon

Step-by-step explanation:

Simply divide the cost by its corresponding amount in gallons

15.77 ÷ 4.75 = 3.32

19.92 ÷ 6 = 3.32

etc etc

Ok please help me and no links or I will report you

Answers

Answer:

B 33

Step-by-step explanation:

im assuming its multiplication because it says “product” so its 33. 846/25 reduces to 33.84 soo 33.

Can someone help with number 4 please

Answers

Answer:

.(0,4,3,1,2,5)..............

Frida owed
$75
on
her credit card. Then she charged
$21
more. What was her new
balance?

Answers

Answer

This problem can be translated as: $75+21$
$75+21=\$ 96$
She already owed 75 dollars and then she charged 25 dollars more on card she already owed money to
Answer: -96 dollars owed on her credit card

Find the value of this expression if x = 1 and
y=-7.
xy
-9

Answers

Answer:

the answer is 7/9............

given..

expression is x^2y/-9

value of x=1

value of y=-7

then.... putting value of x and y in the given equation...

we get .

={1^2*(-7)}/-9

={1*(-7)}/-9

=(-7)/-9

=7/9

Step-by-step explanation:

x²y/-9

1²(-7)/-9

-7/-9

7/9.

hope this helps you.

jamarius 5th grade class was working on a reading project during the school year he wants to read 22 pages for 125 days if jamarius wants to meet his goal how man books will he have to read

Answers

Answer:

2750 pages

Step-by-step explanation:

but i am not sure how many books exactly .

(T^3 - T)/a = b make T the subject of the formula​

Answers

(t^3-t)/a=b because a t the simple of questions

NO LINKS OR ASSESSMENT!!!

Part 2: Graph a function when give the following Domain and Range:​

Answers

Answer:

Step-by-step explanation:

The domain is the x value between - 5 and 7

The range is the y value between -2 and 6

You can find all sorts of definitions for the domain and range, but in this example it is really straight forward.  If you put - 5 into the function, you get -2. If you put 7 into the function, you get 6. Now just draw a line between the two end points.

9514 1404 393

Answer:

  see attached

Step-by-step explanation:

The point at the left end of the domain is not included in the function, but the function includes the limits of its range. One such function is shown in the attachment.

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