Find the exact value pf cos 2x if sin x = - 4/5 (Quadrant III)

Answers

Answer 1

Answer:

[tex]\displaystyle \cos(2x)=-\frac{7}{25}[/tex]

Step-by-step explanation:

We want to find:

[tex]\displaystyle \cos(2x)\text{ given that }\sin(x)=-\frac{4}{5}[/tex]

And x is in QIII.

Recall that sine is the ratio of the opposite side to the hypotenuse.

Therefore, the adjacent side is (we can ignore the negative for now).

[tex]a=\sqrt{5^2-4^2}=\sqrt{25-16}=\sqrt{9}=3[/tex]

So, the adjacent side is 3, the opposite side is 4, and the hypotenuse is 5.

Using the double angle identity, we can rewrite:

[tex]\cos(2x)=\cos^2(x)-\sin^2(x)[/tex]

Since x is in QIII, cosine is positive, sine is negative, and tangent is negative.

Using the above values, we can conclude that:

[tex]\displaystyle \cos(x)=\frac{3}{5}\text{ and } \sin(x)=-\frac{4}{5}[/tex]

Substitute:

[tex]\displaystyle \cos(2x)=\Big(\frac{3}{5}\Big)^2-\Big(-\frac{4}{5}\Big)^2[/tex]

Evaluate:

[tex]\displaystyle \cos(2x)=\frac{9}{25}-\frac{16}{25}=-\frac{7}{25}[/tex]


Related Questions

(2+3) (4-1) simplify

Answers

Step-by-step explanation:

Given

(2+3) (4-1)

= 5 * 3

= 15

Hope it will help :)

Answer:

15

Step-by-step explanation:

(2+3) (4-1)

(5) (3)

15

12. A circle has a center at C(2,5) and a point on the circle has coordinates A(8, 13). Could the point B lie on
the same circle if lies at B(9.1)? Justify.

Answers

Answer:

No.

Step-by-step explanation:

A circle is defined as a figure in which all points are equidistant from the center, or C.  In order to determine how far points A and B are from the center, we must first find the difference in positioning from (2,5) to each point and then use Pythagorean Theorem to calculate the length of the hypotenuse.  Point A establishes that the radius of the circle must be 10 units, and Point Bis only about 8 units away.

A student is conducting a probability experiment and wants to know the total number of outcomes for the experiment. The student's experiment is comprised of three events
• rolling a six-sided number cube • •flipping a coin
• rolling a six-sided number cube again

How many outcomes are possible in this experiment?

A. 14
B. 24
C. 72
D. 38​

Answers

Answer:So to get a 6 when rolling a six-sided die, probability = 1 ÷ 6 = 0.167, or 16.7 percent chance. So to get two 6s when rolling two dice, probability = 1/6 × 1/6 = 1/36 = 1 ÷ 36 = 0.0278, or 2.78 percent.

Step-by-step explanation:

Answer:

C.72

Step-by-step explanation:

rolling a six-sided number cube(6) x flipping a coin(2) x  rolling a six-sided number cube again(6)= 72

6x6= 36

         36 x 2 = 72

6x2=12

12 x 6 = 72

List all the 4-digit even numbers that can be created by rearranging these number tiles.
3
4
7
2

Answers

Answer:

3472

3274

3742

3724

7342

7324

7234

7432

4372

4732

2374

2734

i found this much

These are the 12 possible 4-digit even numbers that can be created by rearranging the number tiles (3, 4, 7, 2).

To create 4-digit even numbers by rearranging the given number tiles (3, 4, 7, 2), we need to consider the following conditions:

The last digit must be an even number (2 or 4).The thousand digits cannot be 0.

Considering these conditions, the possible 4-digit even numbers that can be formed are:

   2347

   2374

   3247

   3274

   3427

   3472

   4237

   4273

   4327

   4372

   4723

   4732

These are the 12 possible 4-digit even numbers that can be created by rearranging the number tiles (3, 4, 7, 2).

Learn more about the even numbers here:

https://brainly.com/question/2142825

#SPJ4

Simplify the ratio 30:45​

Answers

Answer:

2:3

Step-by-step explanation:

Here is the math to illustrate better:

30/15 = 2 and 45/15 = 3

Thus, 30:45 ratio simplified is 2:3

Answer:

2/3

Step-by-step explanation:

There 2 ways:-

The simple way in 2 steps

1.divide  by 5

2. then divide by 3

The complicated way is to divide by 15

Express the recurring decimal 0.136 as a fraction in its simplest form.
Write your working in the box, below, and use x in the working.
Write fractions using the / sign. Eg you would write as 1/2

Answers

Answer = 136/999
Explanation -
X = 0.136136136...
10x = 1.36136136
100x = 13.6136136...
1000x = 136.136136..
1000x - x = 999
136/999

Forgot how to solve, i need help man..

Answers

Answer:

3x + x + 100° = 180°

⇔ 4x = 80°

x = 20°

Step-by-step explanation:

The store is offering 15% discount. The regular price of a T shirt is $23 , what is the discount?

Answers

Answer:

$3.45

Step-by-step explanation:

15% of 23 is 3.45

19.55$ hope this helps

4) Find the area.
7 points
7 in
18 in
10 in
18 in
236
180
125
56

Answers

Answer: its 236

Step-by-step explan

This recipe makes 12 flapjacks.
How much of each ingredient is needed to make 30 flapjacks by following this recipe?

Recipe: Makes 12 flapjacks
140 g margarine
120 g sugar
100 mL syrup
240 g oats
50 g raisins

Answers

Ingredients for 30 flapjacks:

margarine = 350g

sugar : 300g

syrup :250g

oats :  600g

raisins : 125g

What are the ingredients needed for 30 flapjacks?

The first step to determine the amount of ingredients needed to make one flapjack.

Ingredients for one flapjack:

margarine = 140 / 12

sugar : 120 / 12

syrup : 100 / 12

oats : 240 / 12

raisins : 50 / 12

Ingredients for 30 flapjacks:

margarine = (140 / 12) x 30 = 350g

sugar : (120 / 12 ) x 30  = 300g

syrup : (100 / 12) x 30 = 250g

oats : (240 / 12) x 30 = 600g

raisins : (50 / 12) x 30 = 125g

To learn more about division, please check: https://brainly.com/question/13281206

#SPJ1

The radius of a circle is 3 units.

Answers

the diameter is twice to number of the radius so 6 would be ur answer

expand 2x(5x-2)
answer needed asap

Answers

Answer:

10[tex]x^{2}[/tex] - 4x

Step-by-step explanation:

Answer:

10x^2-4x

Step-by-step explanation:

Information is given about a polynomial f(x) whose coefficient are real numbers. Find the remaining zeros of f.

Degree 3; zeros: -2,4-i

Please help!

Answers

Answer:

Remaining zeros x= 4+i

Step-by-step explanation:

since complex roots always occur in conjugate pairs.

so if one root is 4-i the other one will be 4+i

8th grade math, please help.

Answers

Answer:

140 degrees

Step-by-step explanation:

because they're congruent


since this is no where on here

Answers

Answer:

B)

Hope that helps! Or is it for our own good? Either way, thanks!

Step-by-step explanation:

Answer:BHope this helps!! ♥︎brainliest is always appreciated ^-^

If X + 3Y = 5 and 2X - Y = 3, then X is equal to

Answers

Answer:

X=2

Y=1

That's the answer

Negative X plus negative one equals 3X plus -5 what is X

Answers

If this is the equation

-x-1=3x-5

then it should be x=1

Pleases help with 4-9!

Answers

Step-by-step explanation:

The answer is

4_

[tex]m = \frac{4 - 0}{0 - ( - 2)} = \frac{4}{2} = 2[/tex]

9_

[tex]m = \frac{3 - 0}{0 - 4} = \frac{ - 3}{4} [/tex]

ILL GIVE BRAINLIEST

SHOW ALL WORK

Answers

Answer:

9/20 mile^2

Step-by-step explanation:

9/10 x 1/2 = 9/20

Answer:

The area of the field is [tex]\frac{9}{20}[/tex] [tex]miles^{2}[/tex]

Step-by-step explanation:

To get the area, multiply the length and the width together: [tex]\frac{9}{10}[/tex] * [tex]\frac{1}{2}[/tex] = [tex]\frac{9 * 1}{10*2}[/tex] = [tex]\frac{9}{20}[/tex][tex]miles^{2}[/tex].

find the derivative of f(x) = 6 / x at x = -2.

Answers

Answer:

Substitute the given value into the function and evaluate.

−3

Step-by-step explanation:

I think I'm not really sure but use math-way it helps a lot

Round 291 to the nearest hundredth

Answers

Answer:

291 rounded to the nearest hundredth = 291.00

Step-by-step explanation:

QUESTION 8
In this question, you will be assessed on the quality of your organisation, communication and
accuracy in writing
A rod is 4 yards long and another rod is 1į yards long.
What is the total length of these rods in inches?
You must show all your working.
(3 + 2 OCW]
You are given that:
1 yard = 3 feet
1 foot = 12 inches

Answers

Answer:

180

Step-by-step explanation:

First you do 3 feet or 36 inches and multiply that by 5 to get 180.

a class has eight boys and 12 girls. what is a ratio of boys to girls?​

Answers

Answer:

8:12

Step-by-step explanation:

Answer:

8:12

= 2:3

hope

this

helps

1. Find the area of the shaded sector.
2. Find the length of the arc defined by the sector.

Answers

Answer:

1. 150π sq.ft  2. 10π ft

Step-by-step explanation:

Part 1

Equation: Area of a sector = [tex]\frac{x}{360}[/tex] × π[tex]r^{2}[/tex]

Where:

x = internal angle

r = radius of circle

Values from problem:

x = 60

r = 30

Plug values into equation:

Area of sector = [tex]\frac{60}{360}[/tex] × π[tex]30^{2}[/tex]

Simplify:

60 divided by 30 equals [tex]\frac{1}{6}[/tex] and 30 squared equals 900 so...

[tex]\frac{1}{6}[/tex] × 900π

900π divided by 6 equals 150π so...

[tex]\frac{900}{6}[/tex] × π = 150π

150π sq. ft

Part 2

Equation: Arc length = [tex]\frac{x}{360}[/tex] × 2πr

Where:

x = internal angle

r = radius of circle

Values from Problem:

x = 60

r = 30

Plug values into equation:

Arc length = [tex]\frac{60}{360}[/tex] × 2π30

Simplify:

60 divided by 360 equals [tex]\frac{1}{6}[/tex], and 2π × 30 equals 60π so...

[tex]\frac{1}{6}[/tex] × 60π

60π divided by 6 is 10π

[tex]\frac{60}{6}[/tex]π = 10π

10π ft

The radius of a circle measures 12 centimeters.
What is the circumference of the circle?

Answers

Answer:

C=24π

Step-by-step explanation:

C=2πr

C=2π12

C=24π

≈75.39

1. Find the slope of the line that passes through the points (9, 7) and (2, 9).
11
16
7
2
2
-7
7
2

Answers

Answer:

Step-by-step explanation:

Slope of line passing through (x₁, y₁) and (x₂, y₂) = (y₂-y₁)/(x₂-x₁)

Slope of line passing through (9, 7) and (2, 9) = (9-7)/(2-9) = -2/7

Answer:

The slope is [tex] - \frac{2}{7} [/tex]

_

Step-by-step explanation:

☆Remember: [tex]m =  \frac{y_2 - y_1}{x_2 - x_1} [/tex]

---

☆We need to find the slope . So just plug in according to the slope formula!

[tex]m =  \frac{9 - 7}{2- 9} = \frac{ \: \: 2}{ - 7} = - \frac{2}{7} [/tex]

---

▪Happy To Help <3

Suppose y varies directly with x, and y=98 when x=14. Write the direct
variation equation that relates x and y.

Answers

Answer:   y = 7x

===========================================================

Explanation:

Since y varies directly with x, this means y = kx for some constant k.

Plug in y = 98 and x = 14 to solve for k

y = kx

98 = k*14

98/14 = k

7 = k

k = 7

Therefore, y = kx updates to y = 7x which is the equation we're after.

Answer:

y = 7x

Step-by-step explanation:

The general formula for direct variation is y = kx, where k is the constant of proportionality.  If y = 98 when x = 14, then k must be 98/14. or 7, and so

y = 7x is the desired direct variation equation.

Find the Y intercept of the following quadratic function.​

Answers

Answer:

The Y-intercept is 6

Step-by-step explanation:

Please solve this problem for me.

Answers

Answer:

It is 63 or 63/1. Billy used change in x over change in y, and the correct formula for slope is the change in y over the change in x.

He might have done it backwards.

1/63

and could be 63 miles in 1 hour

63/1.

Because the graph looks good. (i think)

A spinner is divided into sections of equal size, some of which are red, some are blue, and the remaining are green. The probability of the arrow landing on a red section is 40%. The probability of the arrow landing on a blue section is 25%.

What is the probability of the arrow landing on a green section?

Group of answer choices

35%

65%

25%

50%

Answers

Answer:

35%

Step-by-step explanation:

X=the probability of the arrow landing on a green section.

Equation:

40+25+ x = 100

65 +x = 100

(65-65) + x = 100-65

X= 35

Hope this helps!

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