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

Solve the system using elimination. x – y = –5 3x + y = 1
(–1, 4)
(–1, 2)
(2, –2)
(–3, 4)

Answers

Answer:

(–1,4)

Step-by-step explanation:

x – y = –5

3x + y = 1

You omit Ys due to their positive and negative signs and you got

4x = –4===> x= –1

and now place –1 inside the upper linear equation and there you have the Y, look

–1 – Y= –5===> –Y= –4===> Y = 4

(–1,4)

heeeeeeeeeeeeelp meee

Answers

Answer: i need the formula and i got you.

Step-by-step explanation:

Estimate 19.625-6.77 by first rounding each number to the nearest tenth.

Answers

Answer:

13

Step-by-step explanation:

1. Round 19.625 up to 20.

2. Round 6.77 up to 7.

3. Calculate the equation. Ans is 13.

Find the distance between the two points in simplest radical form. (-6,1) and (−8,−4)

Answers

Answer: 5

Step-by-step explanation: I think it is 5

Order the following integers from smallest (left side) to biggest (right
side):
20, 0, 22, -35, 100, -59

Need help please

Answers

-59, -35, 0, 20, 22, 100

The functions f (x) = 1/2x-3 and g(x) = -2x+ 2 intersect
at x = -2. True or false?

Answers

9514 1404 393

Answer:

  False

Step-by-step explanation:

f(-2) = (1/2)(-2) -3 = -1 -3 = -4

g(-2) = -2(-2) +2 = 4 +2 = 6

The function values are not the same at x=-2, so the graphs do not intersect there.

__

The graphs intersect at x=2.

When 100 engines are shipped, all of them are free of defects. Select a written description the complement of the given event
A) At most one of the engines is defective.
B) All of the engines are defective.
C) At least one of the engines is defe
D) None of the engines are defective

Answers

Answer:

Option C

Step-by-step explanation:

Suppose that we have a given proposition p

We define the complement as:

"NOT p" or ¬p

So, if p is:

the dog is red

the complement is

the dog is NOT red.

The principal rule to work with this is:

if p is true, then ¬p is false

if p is false, then ¬p is true.

Here the proposition is:

p = "When 100 engines are shipped, all of them are free of defects."

When this is this is true, ¬p must be false.

when this is false, ¬p must be true.

Let's analyze the given options, first the incorrect ones:

A: "At most one of the engines is defective."

here if we have for example, two defective engines, then this proposition and the original proposition are false.

B: " All of the engines are defective."

Here if there is one defective engine, then this is false, and also is the original proposition.

D: "None of the engines are defective"

When the original proposition is true "When 100 engines are shipped, all of them are free of defects.", this proposition is also true (because none of the engines are defective)

Finally, the corrrect one

C "At least one of the engines is defective"

When the original proposition is true, there are no defective engines, so this is false.

While, if this is true, there is at least one defective engine, so the original proposition is false.

Then this is the correct option:

¬p = "At least one of the engines is defective"

______are used to represent an unknown quantity in a mathematical expression.

Answers

Answer:

Variables are used to represent an unknown quantity in a mathematical expression.

Step-by-step explanation:

Variables are used to represent an unknown quantity in a mathematical expression.For example : x + 2 = 4, here x is the variable.We can denote variable by any alphabet i.e, a,b,c,d etc.

Which one is a better deal?
a 3 pack of notebooks for $4.50
Or a 12 pack of notebooks for $15.00

Answers

12 pack is a better deal

how many crores are there in 20 million​

Answers

Answer:

20 million = 2 crore

Step-by-step explanation:

Here we will show you how to convert 20 million to crores (twenty million in crores). This may be useful if you for example want to convert 20 million rupees to crore rupees or 20 million dollars to crore dollars.

In some parts of the world like the United States, large numbers are separated with commas in three-digit-interval format like this:

...,BBB,MMM,TTT,HHH

BBB = billions

MMM = millions

TTT = thousands

HHH = hundreds

In certain parts of Asia, the format is a little different. From right to left, it starts out with three digits followed by a comma like the US, but after that, it is in intervals of two digits like this:

..,AA,CC,LL,TT,HHH

AA = arabs

CC = crores

LL = lakhs

TT = thousands

HHH = hundreds

Below we have displayed 20 million with the two number systems, based on the information above:

MM,TTT,HHH

20,000,000

=

C,LL,TT,HHH

2,00,00,000

When you match up 20 million with the C,LL,TT,HHH format above, you can see what 20 million is in crores. The answer to 20 million in crores is as follows:

20 million

= 2 crore

helppppppppppppppppppppppppppppppppppppppp

Answers

Answer:

the total square footage = 194

1.88 x 194 = 364.72

Step-by-step explanation:

Area for triangle ends.

A = [tex]\frac{2.5 (8)}{2}[/tex]   (Times two, because there are two ends.)

Base of prism = 8 x 10 = 80

Sides of prism = 2(10 x 4.7 ) = 94  (What's the 2?  There's two of them)

Add all together : 10 + 10 + 80 + 94 = 194

1.88 x 194 = 364.72

Solve: 3x - 1 = 8(x + 1) + 1
O A. x= -
3
5
O B. x= -2
O C. x = -
CT 00
O D. There are infinitely many solutions.

Answers

Answer:

x=-2

Step-by-step explanation:

3x-1=8x+8+1

3x-1 = 8x+9

3x-1+1=8x+9+1

3x= 8x+10

3x-8x=8x+10-8x

-5x=10

-5x ÷-5

10 ÷-5

x=-2

The parametric equations for the paths of two projectiles are given. At what rate is the distance between the two objects changing at the given value of t? (Round your answer to two decimal places.) x1 = 10 cos(2t), y1 = 6 sin(2t) First object x2 = 4 cos(t), y2 = 4 sin(t) Second object t = π/2

Answers

Answer:

-  [tex]\frac{4}{\sqrt{29} }[/tex]

Step-by-step explanation:

The equations for the 1st object :

x₁ = 10 cos(2t),  and  y₁ = 6 sin(2t)

2nd object :

x₂ = 4 cos(t), y₂ = 4 sin(t)

Determine rate at which distance between objects will continue to change

solution Attached below

Distance( D )  = [tex]\sqrt{(10cos2(t) - 4cos(t))^2 + (6sin2(t) -4sin(t))^2}[/tex]

hence; dD/dt = - [tex]\frac{4}{\sqrt{29} }[/tex]

the percentage of people under the age of 18 was 23.5% in New York City, 25.8% in Chicago, and 26% in Los Angeles.

If one person is selected from each city, what is the probability that all of them are under 18?

Answers

Answer:

0.0158 = 1.58% probability that all of them are under 18.

Step-by-step explanation:

Probability of independent events:

If three events, A, B and C are independent, the probability of all happening is the multiplication of the probabilities of each happening, that is:

[tex]P(A \cap B \cap C) = P(A)P(B)P(C)[/tex]

The percentage of people under the age of 18 was 23.5% in New York City, 25.8% in Chicago, and 26% in Los Angeles.

This means that [tex]P(A) = 0.235, P(B) = 0.258, P(C) = 0.26[/tex]

If one person is selected from each city, what is the probability that all of them are under 18?

Since the three people are independent:

[tex]P(A \cap B \cap C) = 0.235*0.258*0.26 = 0.0158[/tex]

0.0158 = 1.58% probability that all of them are under 18.

How many boxes could you stack safely on a pallet if the pallet is 5 feet deep, five feet across, every box. is 1 x 1 and the maximum safe stacking height is 5 boxes? *

Answers

Answer:

25 boxes could be stacked safely on the pallet.

Step-by-step explanation:

To determine how many boxes could you stack safely on a pallet if the pallet is 5 feet deep, five feet across, every box is 1 x 1 and the maximum safe stacking height is 5 boxes, the following calculation should be performed:

Pallet = 5 x 5 = 25 square feet

Box = 1 x 1 = 1 square foot

25/1 = 25

Therefore, 25 boxes could be stacked safely on the pallet.

What's the lateral area of the following cone?
11 cm
10 cm

511.23 cm
55 cm?
110.02 cm?
189.75 cm?

Answers

Answer:189.75

Step-by-step explanation:

The lateral area of the cone for the height of 11 cm and diameter 10 cm is given by option D. 189.75 cm²

To calculate the lateral area of a cone,  find the curved surface area.

The lateral area of a cone can be calculated using the formula:

Lateral Area = π × r × l

where:

π is the mathematical constant pi (approximately 3.14159)

r is the radius of the base of the cone

l is the slant height of the cone

Height (h) = 11 cm

Diameter (d) = 10 cm

First, we need to find the radius (r) and the slant height (l).

The radius (r) is half of the diameter:

r

= d / 2

= 10 cm / 2

= 5 cm

The slant height (l) can be found using the Pythagorean theorem:

l² = r² + h²

l² = 5² + 11²

l² = 25 + 121

l² = 146

l = √146

 ≈ 12.083 cm

Now, calculate the lateral area:

Lateral Area = π × r × l

Lateral Area = 3.14159 × 5 cm × 12.083 cm

Lateral Area ≈ 189.75 cm²

Therefore, the lateral area of the cone is approximately 189.75 cm². The correct answer is C) 189.75 cm²

learn more about  lateral area here

brainly.com/question/30196078

#SPJ2

The square root of the variance is called the: standard deviation beta covariance coefficient of variation

Answers

Answer:

standard deviation

Step-by-step explanation:


ABCD is a square of side 12 cm. It is formed from two rectangles AEGD and
EBCG. H is a point on AD and F is a point on BC.
Find the area of EFGH.

Answers

Answer:72 [tex]cm^{2}[/tex]

Solution 1:

Step 1: Find EF use Pythagorean theorem

[tex]EF^{2} = EB^{2} + BF^{2}[/tex]

[tex]EF^{2} = 6^{2} + 6^{2}[/tex]

EF = [tex]\sqrt{6^{2} + 6^{2} }[/tex] = 6[tex]\sqrt{2}[/tex] cm

Step 2: The area of EFGH = [tex]EF^{2}[/tex]= [tex](6\sqrt{2} )^{2}[/tex] = 72

Solution 2: See that the area of EFGH is equal [tex]\frac{1}{2}[/tex] the area of ABCD

The area of ABCD = 12x12 = 144

Thus, the area of EFGH = 144: 2 = 72:)

Have a nice day!

Jonathon looked at the picture frame below and computed the following sum 8 3/4 +{-4}. What value did he find

Answers:

x
2y
y
2 x

Answers

Answer:

he found y value

Step-by-step explanation:

y value would be 8 3/4 + (-4) which is equivalent to 8 3/4 - 4 = 4 3/4

HELPPP PLEASEEE! I tried everything from adding to dividing, subtracting, multiplying but still no correct answer. Can someone help me out here please? I am not sure where to start either now. Thank you for your time.

Answers

36 jersey with green

If an odd number is less than 15, then it is prime

Answers

Answer:

False

Step-by-step explanation:

To show that this is false, all we have to do is find one example.

9 is an odd number less than 15

9 is composite

9 =3*3

Let P denote the set of primes and E the set of even integers. As always, Z and N denote the integers and natural numbers, respectively. Find equivalent formulations of each of the following statements using the notation of set theory

a. √2 is a real number but not a rational number.
b. Every integer is a rational number.
c. 2 is an even prime number.

Answers

Answer:

sorry i dont know this answer

It takes 5 hr for 2 bricklayers to build a park wall. How long would it take 8 bricklayers to complete the job?

Answers

1 hour and 25 mins
It takes 1 hour and 25 mins to complete the 8 bricklayers job

53:28
Nathan and Jordan design surveys to determine the average amount of time bicyclists in a race spend training each
week. Nathan surveys every fifth bicyclist crossing the finish line after a race. Jordan surveys the first five bicyclists to
finish the race. Which best explains which sample is likely to be the most valid?
Nathan's because his sample was more random
Jordan's because his sample was more random
Nathan's because his sample contained elements of the population
Jordan's because his sample contained elements of the population

Answers

Answer:

Nathan's because his sample was more random  

Step-by-step explanation:

Nathan's survey could be described as a Systematic random sampling technique whereby every 5th observation taken as a sample from the population. With these technique we have a more random observation than with.

Answer:

C

Step-by-step explanation:

Please help me quick

Answers

Answer:

I belive it has no x intercepts

it looks weird, but it can be a function. the x-intercept and the y-intercept can also be found in the table above.

to draw a line that can represent a function with these point, we would need to cross y=0 multiple times, so it will have more then one x-intercept.

option A

key takeaway: just draw stuff you find complicated:)

A sample of 24 observations is taken from a population that has 150 elements. The sampling distribution of is _____. an. approximately normal because is always approximately normally distributed b. approximately normal because the sample size is large in comparison to the population size c. approximately normal because of the central limit theorem d. normal if the population is normally distributed

Answers

Answer:

d. normal if the population is normally distributed

Step-by-step explanation:

Central Limit Theorem

The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

In this question:

Sample size less than 30, so only will be normal if the population is normally distribution, and thus the correct answer is given by option d.

I need help solving this problem .

Answers

Step-by-step explanation:

here is the answer to your question

Someone please help me

Answers

Answer:

[tex]x < 4368 \frac{8}{19} [/tex]

Step-by-step explanation:

[tex]28x < 83000 + 9x[/tex]

[tex]28x - 9x < 83000[/tex]

[tex]19x < 83000[/tex]

[tex]x < 4368 \frac{8}{19} [/tex]

Which equation represents a line which is parallel to the line y = -7x - 8?
7x + y = -3
x+ 7y = 7
y - 7x = 6
x- -7y = -28

Answers

Answer:

7x+y=-3

Step-by-step explanation:

if m is the slope of a line, then the slope of its parallel line will have the same slope m,

in the given equation, y=-7x-8, the slope is -7

among the options, 1st option has a slope of -7, since,

7x+y=-3

or, y=-7x-3

Answered by GAUTHMATH

Can you help me answer this question? Screenshot is added.

Answers

9514 1404 393

Answer:

  (c)

Step-by-step explanation:

  [tex]\displaystyle\sqrt[3]{xy^5}\sqrt[3]{x^7y^{17}}=\sqrt[3]{x^{1+7}y^{5+17}}=\sqrt[3]{x^6x^2y^{21}y}=\sqrt[3]{x^6y^{21}}\sqrt[3]{x^2y}\\\\=\boxed{x^2y^7\sqrt[3]{x^2y}}[/tex]

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