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2 years ago

Find an exact value.

Mathematics

1 answer:

leonid [27]2 years ago

7 0

Answer:

(√2 - √6) / 4

C. square root of two minus square root of six divided by four.

Step-by-step explanation:

sine of negative eleven pi divided by twelve.

We have :

sin(-11π/12)

sin((4 - 15)π / 12) = sin(4π/12 - 15π/12)

sin(4π/12 - 15π/12) = sin(π/3 - 5π/4)

Recall:

Angle difference formula:

sin(A - B) = sinAcosB - sinBcosA

Hence,

sin(π/3 - 5π/4) = sin(π/3) cos(5π/4) − sin(5π/4) cos(π/3)

From trigonometry:

sinπ/3 = √3/2

cos5π/4 = -√2/2

sin5π/4 = -√2/2

cos π/3 = 1/2

(√3/2) (-√2/2) − (-√2/2) (1/2)

-√6/4 - -√2/4

-√6/4 + √2/4

√2/4 - √6/4

(√2 - √6) / 4

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It took a plane 2 hours to go from Dallas to NY with the head wind and 1.5 hours to get back with the tail wind. If the speed of

vladimir2022 [97]

Answer:

360 miles

Step-by-step explanation:

let speed of plane be x

speed of wind be c

Also note D = RT, where

D is distance and R is rate and T is time

<u>For First Leg:</u>

we can write:

(x - c) * 2 = D

2x - 2c = D

<u>For Second Leg:</u>

we can write:

(x+c)*1.5 = D

1.5x + 1.5c = D

We can equate and write:

2x - 2c = 1.5x + 1.5c

0.5x = 3.5c

We know Speed of Wind, c, is 30, so we have:

0.5x = 3.5(30)

0.5x = 105

x = 105/0.5 = 210 [speed of airplane]

We know distance is

D = 2x - 2c

D = 2(210) - 2(30)

D = 420 - 60

D = 360 miles

The distance is 360 miles

6 0

2 years ago

Sarah makes 5 ribbons the first day. On the second day she doubles the number of

sdas [7]

20 ribbons

Explanation:
1st day— 5 ribbons
2nd day—2 x 5 = 10 ribbbns
3rd day— 2 x 10 = 20

Hope this helps

7 0

2 years ago

Read 2 more answers

An airplane is flying at 32,000 feet when it starts its descent. It is descending at a rate of 2,000 feet per minute. Let x repr

velikii [3]

Answer:

equation: y = 32000 - 2000x

0 = 32000

1 = 30000

2 = 28000

3 = 26000

4 = 24000

Step-by-step explanation:

3 0

2 years ago

What will be 66 2/3 as a percent explanation

VashaNatasha [74]

66.666666 repeated decimal
You would keep the 66 as is, and divide 2 by 3. That equals 0.66666666666 repeated, so the answer would be 66.666666 (rounded: 66.67)

6 0

3 years ago

A plane flying horizontally at an altitude of 2 mi and a speed of 540 mi/h passes directly over a radar station. Find the rate a

Rasek [7]

Answer:

The plane's distance from the radar station will increase about 8 miles per minute when it is 5 miles away from it.

Step-by-step explanation:

When the plane passes over the radar station, the current distance is the altitude h = 2. Then it moves b horizontally so that the distance to the station is 5. We can form a rectangle triangle using b, h and the hypotenuse 5. Therefore, b should satisfy

h²+b² = 5², since h = 2, h² = 4, as a result

b² = 25-4 = 21, thus

b = √21.

Since it moved √21 mi, then the time passed is √21/540 = 0.008466 hours, which is 0.51 minutes. Note that in 1 minute, the plane makes 540/60 = 9 miles.

The distance between the plane and the radar station after x minutes from the moment that the plane passes over it is given by the function

$f(x) = \sqrt{((9x)^2 + 2^2)} = \sqrt{(81x^2+4)}$

We have to compute the derivate of f in x = 0.51. The derivate of f is given by

$f'(x) = \frac{162x}{2\sqrt{81x^2+4}}$

also,

$f'(0.51) = \frac{162*0.51}{2\sqrt{81*0.51^2+4}} = 8.2486$

The plane's distance from the station will increase about 8 miles per minute.

4 0

2 years ago