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3 years ago

−20cos 2 x−3cosx=−2 answer in decimals

Mathematics

2 answers:

Sergeu [11.5K]3 years ago

7 0

Here is your answer. 0.117658

Airida [17]3 years ago

3 0

Well, first of all, the equation in your question isn't clear. I decided that you intended to write the equation

-20 cos²(x) - 3 cos(x) = -2

If this is not the correct equation, then you should stop reading right here. Everything else from here on is nonsense, and you should report my answer.

= = = = =

If that IS the correct equation, then ...

Multiply each side by -1 . . . 20 cos²(x) + 3 cos(x) = 2

Subtract 2 from each side . . . 20 cos²(x) + 3 cos(x) - 2 = 0

This is a quadratic equation in 'cos(x)' . I messed around for a while trying to factor it, and then I gave up and used the Quadratic Formula.

Like any other quadratic equation, this one has two roots:

(1). cos(x) = -119/40 or -0.475

(2). cos(x) = 7/40 or 0.175

For the first one, the angle 'x' is 118.36° or 241.64°

For the second one, the angle 'x' is 79.92° or 280.08°

So the original equation ... the one with all the cosines in it ... actually has four (4) solutions.

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an isosceles triangle has congruent sides of 20cm. the base is 10cm. find the height of the triangle.

dolphi86 [110]

Answer:

$\large\boxed{A_\triangle=25\sqrt{15}\ cm^2}$

Step-by-step explanation:

Look at the picture.

The formula of an area of a triangle:

$A_\triangle=\dfrac{bh}{2}$

b - base

h - height

We need a length of a height.

Use the Pythagorean theorem:

$leg^2+leg^2=hypotenuse^2$

We have:

$leg=5,\ leg=h,\ hypotenuse=20$

Substitute:

$5^2+h^2=20^2$

$25+h^2=400$ subtract 25 from both sides

$h^2=375\to h=\sqrt{375}\\\\h=\sqrt{(25)(15)}\\\\h=\sqrt{25}\cdot\sqrt{15}\\\\h=5\sqrt{15}\ cm$

Calculate the area:

$A_\triangle=\dfrac{(10)(5\sqrt{15})}{2}=\dfrac{50\sqrt{15}}{2}=25\sqrt{15}\ cm^2$

8 0

3 years ago

Can someone tell me if this adjacent , vertical or linear

babymother [125]

Answer:

adjacent

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5 0

2 years ago

Divide 4^2/4^6

deff fn [24]

Step-by-step explanation:

$= {4}^{2} \div {4}^{6}$

$= {4}^{2 - 6}$

$= {4}^{ - 4}$

Option → C

$\:$

$= {4}^{ - 4}$

$= \frac{1}{ {4}^{4} }$

$= \frac{1}{4 \times 4 \times 4 \times 4}$

$= \frac{1}{256}$

Option → A

6 0

2 years ago

Carol's starting pay for her summer job is $10.25 per hour. Carol earns exactly 3 raises this summer.

zlopas [31]

We know that
1) Carol's starting pay for her summer job is $10.25 per hour
Carol earn per hour=$10.25 per hour

2) For the first rise, she receives a 50 cent-per-hour raise
10.25+0.50=10.75
Carol earn per hour=$10.75 per hour

3) For the second rise, she receives a 10% raise per hour
10.75*1.10=11.825
Carol earn per hour=$11.825 per hour

4) For the third rise, she receives another 50 cent-per-hour raise
11.825+0.50=12.325
Carol earn per hour=$12.325 per hour

5) At the start of next summer. She will be given a 5% raise per hour based on her pay at the end of this summer. 
12.325*1.05=12.94125
Carol will earn per hour=$12.94 per hour

the answer is
$12.94 per hour

4 0

2 years ago

The total of your dinner bill plus tip is 19.00$ You left a 3.00$ tip the 3.00$ tip is what percent of the dinner bill help plzz

Norma-Jean [14]

Answer:

About 15%

Step-by-step explanation:

3 divided by 19 is 0.1578947368421053

0.1578947368421053 multiplied by 100 is 15.78947368421053‬.

7 0

3 years ago

−20cos ​2 ​​ x−3cosx=−2 answer in decimals

−20cos 2 x−3cosx=−2 answer in decimals