In any triangle ABC,Prove by vector method c^2=a^2+b^2-2abcosC​

Answers

Answer 1

Answer:

Let be [tex]\vec A[/tex], [tex]\vec B[/tex] and [tex]\vec C[/tex] the vector of a triangle so that [tex]\vec C = \vec A + \vec B[/tex]. By definition of Dot Product:

[tex]\vec C \,\bullet\,\vec C = (\vec A + \vec B) \,\bullet \vec C[/tex]

[tex]\vec C \,\bullet \,\vec C = (\vec A\,\bullet \,\vec C) + (\vec B \,\bullet \,\vec C)[/tex]

[tex]\|\vec C\|^{2} = [\vec A \,\bullet \,(\vec A + \vec B)] + [\vec B\,\bullet \,(\vec A + \vec B)][/tex]

[tex]\|\vec C\|^{2} = \vec A \,\bullet \, \vec A + \vec B\,\bullet \vec B + 2\cdot (\vec A \,\bullet \, \vec B)[/tex]

[tex]\|\vec C\|^{2} = \|\vec A\|^{2} + \|\vec B\|^{2} + 2\cdot \|\vec A\|\cdot \|\vec B\|\cdot \cos\theta_{C}[/tex]

Step-by-step explanation:

Let be [tex]\vec A[/tex], [tex]\vec B[/tex] and [tex]\vec C[/tex] the vector of a triangle so that [tex]\vec C = \vec A + \vec B[/tex]. By definition of Dot Product:

[tex]\vec C \,\bullet\,\vec C = (\vec A + \vec B) \,\bullet \vec C[/tex]

[tex]\vec C \,\bullet \,\vec C = (\vec A\,\bullet \,\vec C) + (\vec B \,\bullet \,\vec C)[/tex]

[tex]\|\vec C\|^{2} = [\vec A \,\bullet \,(\vec A + \vec B)] + [\vec B\,\bullet \,(\vec A + \vec B)][/tex]

[tex]\|\vec C\|^{2} = \vec A \,\bullet \, \vec A + \vec B\,\bullet \vec B + 2\cdot (\vec A \,\bullet \, \vec B)[/tex]

[tex]\|\vec C\|^{2} = \|\vec A\|^{2} + \|\vec B\|^{2} + 2\cdot \|\vec A\|\cdot \|\vec B\|\cdot \cos\theta_{C}[/tex]


Related Questions

factorize : ( p- q ) cube​

Answers

Answer:

[tex]( {p - q}^{3} ) \\ = {p}^{2} - 3 {p}^{2} q + 3p {q}^{2} - {q}^{3} [/tex]

Hope my answer helped u :)

prove that 2^n+1>(n+2).sin(n)​

Answers

Step-by-step explanation:

F(n)=|sin(n)|+|sin(n+1)|

then

F(n+π)=|sin(n+π)|+|sin(n+π+1)|=|sin(n)|+|sin(n+1)|=F(n)

and

F(π−n)=|sin(π−n)|+|sin(π−n+1)|=|sinn|+|sin(n−1)|≠F(n)

so we must prove when n∈(0,π), have

F(n)>2sin12

when n∈(0,π−1),then

F(n)=sinn+sin(n+1)=sinn(1+cos1)+sin1cosn

and n∈(π−1,π),then

F(n)=sinn−sin(n+1)

How prove it this two case have F(n)>2sin12? Thank you

and I know this well know inequality

|sinx|+|sin(x+1)|+|sin(x−1)|≥2sin1,x∈R

help me besties pls and have a good Bestie

Answers

Answer:

6

Step-by-step explanation:

Area = length x width

Input the numbers:

Area = 78

length = 13

78 = 13 x width

width = 78 / 13

width = 6

If my answer is incorrect, pls correct me!

If you like my answer and explanation, mark me as brainliest!

-Chetan K

Answer:

Width=6m

Step-by-step explanation:

Area=78m^2

Length=13m

width=?(let width be x)

[AREA OF RECTANGLE=length× width]

78=13×x

78=13x

×=6

Complete the table for the given rule.
Rule: y is 0.750.750, point, 75 greater than x
x y
0
3
9

Answers

Answer:

está inglês não dá para entende

Please help me with this on the picture

Answers

9514 1404 393

Answer:

  (-5, 4)

Step-by-step explanation:

The inside corner moves from (2, -2) to (-3, 2). That is 5 is subtracted from the x-coordinate, and 4 is added to the y-coordinate. (x, y) ⇒ (x -5, y +4)

The translation vector can be written horizontally as (-5, 4), or vertically as ...

  [tex]\displaystyle\binom{-5}{4}[/tex]

a car drives at 45 km/h for 75 minutes how far does the car travel

Answers

Answer:

56.25km

Step-by-step explanation:

75min = 5/4 h

distance = speed * time = 45 * 5/4 = 56.25

Determine the critical values for the confidence interval for the population standard deviation from the given values. Round your answers to three decimal places.
n = 12 and c = 0.9.

Answers

Answer:

The answer is "[tex]\chi^2_{L} = 4.575 \ and\ \chi^2_{U}= 19.675[/tex]"

Step-by-step explanation:

[tex]n=12\\\\\ c= 0.9[/tex]

Calculating the level of significance [tex](\alpha) = 1 -c[/tex]

                                                                  [tex]=1-0.9\\\\=0.1[/tex]

Calculating the degrees of freedom:

[tex]df=n-1=12-1=11[/tex]

Calculating the critical value:

Applying the Chi-Square table, the critical values for the two-tailed test with a degree of freedom  (11) for the significance level of [tex]\alpha = 0.1[/tex]:

[tex]\chi^2_{L} = 4.575 \\\\\chi^2_{U}= 19.675[/tex]

Starting with a fresh bar of soap, you weigh the bar each day after you take a shower. Then you find the regression line for predicting weight from number of days elapsed. The slope of this line will be:__________.

Answers

Answer:

The slope will be negative

Step-by-step explanation:

The slope of the regression line tells us about the relationship or behavior of the dependent and independent variables. In the scenario above, where the weight is being compared with the number of days elapsed. What is expected of the weight and quantity of a bar soap each time it is used for a shower is that it will decrease in weight. Therefore, as the number of days increases, and hence, number of showers rise, the weight of soap will decrease. Hence, we'll obtain a negative slope, one in which the increase in a variable leads to decrease in the other.

Calculate the range and the standard deviation for the set of numbers.
6,5, 1, 5, 8, 5, 3, 5, 4,7
The range is
(Simplify your answer.)

Can I please get help with this problem?

Answers

Answer:

When time is short and you just want a rough estimate of the standard deviation, turn to the range rule to quickly estimate the standard deviation value. The standard deviation is approximately equal to the range of the data divided by 4. That's it, simple.

I don’t understand these 3 questions and I need help.

Answers

Not sure about the first one but the second one is option c (or -3). You just have to factor and find the solutions (so it would be -7 and 4 and then u just add them)

For question 39 the answer is c

Answer:

1: A=1

2: -3

3: C

Step-by-step explanation:

1: If 3x+4 is a factor, then -4/3 is equal to x. Substitute it in for x and solve for a.  This gives us A=1.

For the commenter not understanding how I got -4/3: 3x+4 being a factor means that it equals 0. It might help you understand this if you remember that after factoring, like I did for 38 in my photo, we take expressions like x-4 and set them equal to 0 to get x=4, a solution. So, subtract 4 from both sides to get 3x=-4, then divide both sides by 3 to get x alone. Thus, x=-4/3.

2: To find the sum, we first need to find the two solutions. We can factor to get (x+7)(x-4). This gives us x=-7 and x=+4. The solution of these two would be (-7)+4 is -3.

3: B is a close answer, but the signs are wrong on the bottom. Factoring the question would give us 2(x-2) / 2(x^2-x-2). Factoring that equation is 2(x-2) / 2(x+1)(x-2). Simplifying this gives us 1 / x+1.

Sorry for the bad penmanship, I wanted to make it a little clearer for you! I really hope I helped! :)

A well-known brokerage firm executive claimed that 60% of investors are currently confident of meeting their investment goals. An XYZ Investor Optimism Survey, conducted over a two week period, found that in a sample of 100 people, 69% of them said they are confident of meeting their goals. Test the claim that the proportion of people who are confident is larger than 60% at the 0.01 significance level.
The null and alternative hypothesis would be:________
a. H0:μ=0.6H0:μ=0.6
H1:μ≠0.6H1:μ≠0.6
b. H0:μ=0.6H0:μ=0.6
H1:μ<0.6H1:μ<0.6
c. H0:μ=0.6H0:μ=0.6
H1:μ>0.6H1:μ>0.6
d. H0:p=0.6H0:p=0.6
H1:p≠0.6H1:p≠0.6
e. H0:p=0.6H0:p=0.6
H1:p>0.6H1:p>0.6
f. H0:p=0.6H0:p=0.6
H1:p<0.6H1:p<0.6
The test is:________
a. two-tailed
b. left-tailed
c. right-tailed
The test statistic is:_______ (to 3 decimals)
The p-value is:_______ (to 4 decimals)
Based on this we:________
a. Fail to reject the null hypothesis
b. Reject the null hypothesis

Answers

We are testing a hypothesis. So, first we identify the null and the alternative hypothesis, then we find the test statistic, and with the test statistic, the p-value is found.

Null and alternative hypothesis:

Claim the the proportion is of 60%, thus, the null hypothesis is:

[tex]H_0: p = 0.6[/tex]

Test if the proportion is greater than 60%, thus, the alternative hypothesis is:

[tex]H_1: p > 0.6[/tex]

And the answer to the first question is given by option c.

Classification:

We are testing if the proportion is greater than a value, so it is a right-tailed test.

Test statistic:

[tex]z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}[/tex]

In which X is the sample mean, [tex]\mu[/tex] is the value tested at the null hypothesis, [tex]\sigma[/tex] is the standard deviation and n is the size of the sample.

0.6 is tested at the null hypothesis:

This means that [tex]\mu = 0.6, \sigma = \sqrt{0.4*0.6}[/tex]

Survey, conducted over a two week period, found that in a sample of 100 people, 69% of them said they are confident of meeting their goals.

This means that [tex]n = 100, X = 0.69[/tex]

Value of the test statistic:

[tex]z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}[/tex]

[tex]z = \frac{0.69 - 0.6}{\frac{\sqrt{0.4*0.6}}{\sqrt{100}}}[/tex]

[tex]z = 1.837[/tex]

The test statistic is z = 1.837.

p-value:

The p-value of the test is the probability of finding a sample proportion above 0.69, which is 1 subtracted by the p-value of z = 1.837.

Looking at the z-table, z = 1.837 has a p-value of 0.9669.

1 - 0.9669 = 0.0331

The p-value is 0.0331.

Decision:

The p-value of the test is 0.0331 > 0.01, and thus:

a. Fail to reject the null hypothesis

For another example of a problem of a test of hypothesis, you can take a look at:

https://brainly.com/question/24166849

write your answer as an integer or as a decimal rounded to the nearest tenth​

Answers

Answer:

FH ≈ 6.0

Step-by-step explanation:

Using the sine ratio in the right triangle

sin49° = [tex]\frac{opposite}{hypotenuse}[/tex] = [tex]\frac{FH}{FG}[/tex] = [tex]\frac{FH}{8}[/tex] ( multiply both sides by 8 )

8 × sin49° = FH , then

FH ≈ 6.0 ( to the nearest tenth )

Answer:

6

Step-by-step explanation:

sin = opposite/hypotenuse

opposite = sin * hypotenuse

sin (49) = 0,75471

opposite = 0,75471 * 8 = 6,037677 = 6

convert 35 m/s to km/hr

Answers

Hello, there I hope you are having a great day :) Your question was to convert 35 m/s to km/hr the answer would be 126 km/ hr as you would times it by 3.6 to work out your answer.

Hopefully that helps you :)

Which phrase describes an unknown or changeable quality?
3 feet and 7 inches
4 quarts in a gallon
2 o'clock in the afternoon
The height of the building times 1/2

Answers

Answer:

it should be the height of the building time 1/2

Step-by-step explanation:

let me know if its correct or incorrect we'll I hope this help you

please helpppp i need it by tonight its very important

Answers

Answer:

m<1=145

m<2=35

m<3=35

Step-by-step explanation:

measure one is supplementary(the angles add to 180) to measure four.

so we do 180-35=145

measure 2 is congruent to measure four because they are corresponding angles

so measure 2=35

and measure 3 is also congruent to measure 4 because the are corresponding angles

so m<3=35

What is an explicit formula for the geometric sequence -64,16,-4,1,... where the first term should be f(1).

Answers

Answer:

[tex]a_{n} = -64(-\frac{1}{4})^{n-1}[/tex]

it seems like the first term is -64, so lets write the formula accordingly:

a_n = a1(r)^(n-1)

where 'n' is the number of terms

a1 is the first term of the sequence

'r' is the ratio

the ratio is [tex]-\frac{1}{4}[/tex] because -64 * [tex]-\frac{1}{4}[/tex] = 16 and so on...

the explicit formula is :

[tex]a_{n}[/tex] = [tex]-64(-\frac{1}{4} )^{n-1}[/tex]

look at the image below

Answers

Answer:

201.1 km²

Step-by-step explanation:

Surface area of a sphere= 4πr², where r = radius

so,

4πr²

= 4×π×4²

= 64π

= 201.1 km² (rounded to the nearest tenth)

Write a simple algorithm to add two numbers

Answers

Answer:

Write an algorithm to add two numbers entered by user. Step 2: Declare variables num1, num2 and sum. Step 3: Read values num1 and num2. Step 4: Add num1 and num2 and assign the result to sum.

Hope it helped . Here is the answer.

210
To rationalize the denominator of
3.11,You should multiply the expression by which fraction?
11
2- V10
2- 10
3- V11
3- V11

Answers

The answer is The second one because I took this test before and I got it right

We should multiply the expression by √11/ √11 fraction.

What is the fundamental principle of multiplication?

Multiplication is the mathematical operation that is used to determine the product of two or more numbers.

To rationalize this, we multiply both the denominator and denominator by the conjugate of the denominator.

The denominator is 2-√10 and its conjugate is; (2+√10).

(2√10)/(3√11) = (2√10)/(3√11)

                      =  ((2√10)√11/(3√11) √11

                =    (2√110)/33

This is the rationalized expression.  

Learn more about multiplications;

brainly.com/question/14059007

#SPJ7

Find the 97th term of the arithmetic sequence 17, 26,35,...

Answers

Hy mate!!

The answer of your question is in the attachment..!!

.

.

Hope this answer helps you..!!

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Select it as the BRAINLIEST..!!

Where r is the radius of the cylinder and h is the height of the cylinder.
Find the surface area when r is 7 inches and h is 9 inches.




Sa of cylinder= 2(pi)rh + 2(pi)r squared

Answers

Answer:

703.7 in²

Step-by-step explanation:

SA = 2πrh+2πr²

= 2×π×7×9+2×π×7²

= 224π

= 703.7 in² (rounded to the nearest tenth)

Answer:

224π

in²

Step-by-step explanation:

Find the greatest rational number r such that the ratios 8/15 ÷ r and 18/35 ÷ r are whole numbers?

Answers

The answer is "[tex]\bold{\frac{2}{105}}[/tex]", and the further calculation can be defined as follows:

When the "r" is the greatest common divisor for the two fractions.

So, we will use Euclid's algorithm:  

[tex]\to \bold{(\frac{8}{15}) -(\frac{188}{35})}\\\\\to \bold{(\frac{8}{15} -\frac{188}{35})}\\\\\to \bold{(\frac{56-54}{105})}\\\\\to \bold{(\frac{2}{105})}\\\\[/tex]

this is  [tex]\bold{(\frac{8}{15}) \ \ mod \ \ (\frac{18}{35})}[/tex]

we can conclude that the GCD for [tex]\bold{\frac{54}{105}}[/tex], when divided by [tex]\bold{\frac{2}{105}}[/tex], will be the remainder is 0.  Rational numbers go from [tex]\bold{\frac{2}{105}}[/tex] with the latter being the highest.

So, the final answer is "[tex]\bold{\frac{2}{105}}[/tex]".

Learn more:

greatest rational number:brainly.com/question/16660879

Evaluate 3|x|+2x-1 when x = -5.

Answers

Answer:

4

Step-by-step explanation:

To start off, we are going to input our x value into our expression.

3|-5| + 2(-5) - 1

Next, we are going to find the absolute value (always positive) of -5 and multiply 2 and -5.

3(5) - 10 -1

Now, we will multiply 3 and 5.

15 - 10 -1

Finally, we are going to combine our like terms (15, -10, and -1)

4

So! Our final answer for this expression is 4!

Hope this Helps! :)

Have any questions? Ask below in the comments and I will try my best to answer.

-SGO

I need help so what’s 6 divide by 2(1+2)=

Answers

Answer:

9

Step-by-step explanation:

Divide 6 by 2:

3(1+2)

Add 1 and 2:

3 x 3

Multiply 3 by 3:

3 x 3 = 9

Answer:

1

Step-by-step explanation:

6

------

2(1+2)

6

-----

2(3)

6

-----

6

1

Needddd annnsssweeerrr

Answers

Answer:

90in2

Step-by-step explanation:

3x5x6=90

Answer:

C.90

Step-by-step explanation:

first multiply 3 and 5 which is 15 then times it with 6 which equals 90

What is the simplified form of square root 400 x to the power 100

Answers

Step-by-step explanation:

[tex]thank \: you[/tex]

Answer:

20x⁵⁰

Step-by-step explanation:

With the equation √400x¹⁰⁰

we need to take the square root away separately

√400 = √20*20 = 20

Then with x¹⁰⁰

√x¹⁰⁰ = √x⁵⁰*x⁵⁰ = x⁵⁰

So √400x¹⁰⁰ = 20x⁵⁰

hope this helps

terms are there. Divide 51 into three parts in AP so that the largest exceeds the smallest by 10.​

Answers

The first three terms of the Arithmetic Progression are 12, 17 and 22.

For an ARITHMETIC PROGRESSION, AP ;

First term = a

Second term = a + d

Third term = a + 2d

Where, d = common difference ;

If third term exceeds smallest by 10 ;

Third term - first term

a + 2d - a = 10

2d = 10

d = 10/2

d = 5

Sum of the three terms :

a + (a + d) + a + 2d = 51

3a + 3d = 51

d = 5

3a + 3(5) = 51

3a + 15 = 51

3a = 51 - 15

3a = 36

a = 12

The AP would be:

First term, a = 12

Second term, a + d = 12 + 5 = 17

Third term = a + 2(d) = 12 + 10 = 22

Therefore , the first three terms of the AP are :

12, 17 and 22

Learn more about ARITHMETIC PROGRESSION :

https://brainly.com/question/12006170

For U.S. adult males, the mean height is 174 cm with a standard deviation of 5 cm and the mean weight is 86 kg with a standard deviation of 10 kg. Elmer is 185 cm tall and weighs 102 kg. It is most nearly correct to say that

Group of answer choices

Elmer's weight is more unusual than his height

Height has more variation than weight

Elmer's height is more unusual than his weight

Height and weight have the same degree of variation

Answers

Answer:

The answer is

Height and weight have the same degree of variation

Answer:

The Answer. is height and weight have the same degree of variation.

The segments shown below could form a triangle.
A
C
7
9
12
B
А
a
A. True
B. False

Answers

Answer:

TRUE

Step-by-step explanation:

I SEEN SOME ONE ELSE WIT 5 STARS SAY SO(:

The given segment can form triangle. Therefore, the given statement is true.

What is triangle?

A polygon has three edges as well as three vertices is called a triangle. It's one of the fundamental geometric shapes. In Euclidean geometry, each and every three points that are not collinear produce a distinct triangle and a distinct plane. In other words, every triangle was contained in a plane, and there is only single plane that encompasses that triangle.

All triangles are enclosed in a single plane if all of geometry is the Euclidean plane, however this is no longer true in higher-dimensional Euclidean spaces. Unless when otherwise specified, this article discusses triangles within Euclidean geometry, namely the Euclidean plane. The given segment can form triangle.

Therefore, the given statement is true.

To know more about triangle, here:

https://brainly.com/question/14712269

#SPJ7

Please help me with this on the image

Answers

Answer:

Step-by-step explanation:

a). Given expression in the question is,

   [tex]\frac{13822\times 623}{14}[/tex]

   Exact value of the expression will be,

   [tex]\frac{13822\times 623}{14}=615079[/tex]

b). By using approximations to 1 significant figure,

   13822 ≈ 10000

   623 ≈ 600

   14 ≈ 10

   615079 ≈ 60000

   Now use the expression,

   [tex]\frac{13822\times 623}{14}=\frac{10000\times 600}{10}[/tex]

                  = 60000

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