What does the law of cosines reduce to when dealing with a right angle

Answers

Answer 1

Answer:

It is reduced to the equation of the Theorem of Pythagoras.

Step-by-step explanation:

Any triangle can be modelled by this formula under the Law of Cosine:

[tex]b = \sqrt{a^{2}+c^{2}-2\cdot a\cdot c\cdot \cos B}[/tex]

Where:

[tex]a[/tex], [tex]b[/tex], [tex]c[/tex] - Side lengths, dimensionless.

[tex]B[/tex] - Angle opposed to the side [tex]b[/tex], measured in sexagesimal degrees.

Now, let suppose that angle B is a right angle (90º), so that b is a hypotenuse and a and c are legs. Hence:

[tex]\cos B = 0[/tex]

And the equation is reduced to the form of the Theorem of Pythagoras, that is to say:

[tex]b = \sqrt{a^{2}+c^{2}}[/tex]


Related Questions

52°
Х
X
tycoom whoever helps with thos

Answers

Answer:

142

Step-by-step explanation:

The exterior angle of a triangle is equal to sum of the opposite interior angles

x = 52+90

x = 142

An exterior angle of a triangle is equal to the sum of its interior opposite angles.

[tex]\large\bf{{\purple{ \longrightarrow \:\large\rm \: x \: = \: 52 \degree \: + \: 90 \degree }}} \\ [/tex]

[tex]\large\bf{{\purple{ \longrightarrow \:\large\rm \: x \: = \: 142 \degree }}} \\ [/tex]

if tolu collects a loan of #250,000 from a bank at the rate of 11 whole number 1 over 2% interest how much will she pay as interest at the end of the year​

Answers

Answer:

# 28750

Step-by-step explanation:

Intrest = P. A. * Intrest Rate * Time

Intrest = 250000 * 11.5/100 = 28750

There are 45 eighth graders and 20 seventh graders in a school club. The president of this club wants 40% of the club’s members to be seventh graders. How many more seventh-graders must join the club in order to meet the president’s wishes? (Assume that the number of eighth-graders remains the same.)

Answers

Answer: Please Give Brainliest. Thank You!

10 more

The number of seventh-graders that must join the club in order to meet the president's wishes is 10.

Since there are 45 eighth graders and 20 seventh graders in a school club and the president of this club wants 40% of the club’s members to be seventh graders, we need to find the number of seventh graders that will be added to the school club to make their percentage 40 %.

Let the number of seventh-graders to be added be x.

So, the new number of seventh-graders is 20 + x and the new number of people in the club is 45 + 20 + x = 65 + x

Thus, the percentage of seventh graders in the club is thus

[tex]\frac{20 + x}{65 + x} X 100[/tex] %

Since this percentage equals 40 %, we have that

[tex]\frac{20 + x}{65 + x} X 100[/tex]% = 40 %

[tex]\frac{20 + x}{65 + x} = \frac{40}{100} \\\frac{20 + x}{65 + x} = 0.4[/tex]

Cross-multiplying we have

[tex]20 + x = 0.4(65 + x)[/tex]

Expanding the bracket, we have

[tex]20 + x = 26 + 0.4x[/tex]

Subtracting 20 from both sides we have

[tex]x = 26 - 20 + 0.4x\\x = 6 + 0.4x[/tex]

Subtracting 0.4x from both sides, we have

[tex]x - 0.4x = 6\\0.6x = 6[/tex]

dividing both sides by 0.6, we have

x = 6/0.6

x = 10

So, the number of seventh-graders that must join the club in order to meet the president's wishes is 10.

Learn more about percentages here:

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ABCD is a quadrilateral, P Q R and S divide AB, CB, CD and AD in ratio 1:3 respectively. Prove that a//m. (Please hurry up, I will mark you as Brainliest) ​

Answers

Two lines are parallel if they are equidistant from one another. The following proves [tex]a || m[/tex]

[tex]Ratio = 1:3[/tex] means that:

[tex]BP=3PA[/tex]

[tex]BQ=3QC[/tex]

To prove that [tex]a || m[/tex] is to prove that side length SR and side length PQ are parallel because:

[tex]SR = a\\ PQ = m[/tex] --------- See attachment for quadrilateral

Considering [tex]\triangle ABC[/tex], we have: [tex]BP=3PA[/tex]

Divide both sides by PA

[tex]\frac{BP}{PA} = \frac{3PA}{PA}[/tex]

[tex]\frac{BP}{PA} = 3[/tex]

Similarly: [tex]BQ=3QC[/tex]

Divide both sides by QC

[tex]\frac{BQ}{QC} = \frac{3BQ}{QC}[/tex]

[tex]\frac{BQ}{QC} = 3[/tex]

So, we have:

[tex]\frac{BP}{PA} = \frac{BQ}{QC} = 3[/tex]

Express as ratios

[tex]BP:PA = BQ:QC = 3[/tex]

[tex]BP:PA \to[/tex] means point P divided side length BA into 3:1

[tex]BQ:QC \to[/tex] means point Q divided side length BC into 3:1

Thales Theorem states that: A line that divides any two sides of a triangle in the same ratio is parallel to the third side.

The third side of [tex]\triangle ABC[/tex] is [tex]AC[/tex].

This means that: [tex]PQ[/tex] is parallel to [tex]AC[/tex]

Since [tex]AC[/tex] is parallel to [tex]SR[/tex], then [tex]PQ[/tex] is parallel to [tex]SR[/tex]

i.e. [tex]SR || PQ[/tex]

Recall that:

[tex]SR = a\\ PQ = m[/tex]

Hence:

[tex]a || m[/tex] has been proved.

Read more about proof of parallel sides at:

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BC has endpoints B(5,9) and C(-4,-3). Find the coordinates of the midpoint of BC.
I need help !!

Answers

Answer:

(0.5,3)

Hope this helps..Have a good day!!

Add or subtract. Write your answer in scientific notation.
4.2 x 10^6 − 1.2 x 10^5 − 2.5 x 10^5
3.3 x 10^9 + 2.6 x 10^9 + 7.7 x 10^8
8.0 x 10^4 − 3.4 x 10^4 − 1.2 x 10^3

Answers

Answer:

1. 38.3 x 10^5

2. 6.67 x 10^9

3. 4.48 x 10^4

Step-by-step explanation:

4.2 X 10 ^6 - 1.2 X 10^5 - 2.5 x 10^5

For the above question, we need to make the exponents equal

=> 42 x 10^5  -  1.2 x 10^5  -  2.5 x  10^5

SInce, all the exponents are equal, we can now add and subtract the normally.

=> (42 - 1.2 -2.5) x 10^5

=> (42 - 3.7) x 10^5

=> 38.3 x  10^5

So, the answer to the 1st question is 38.3 x 10^5

Next question:

=> 3.3 x 10^9 + 2.6 x 10^9 +7.7 x 10^8

=>  we need to make the exponents equal

=> 3.3 x 10^9 + 2.6 x 10^9 + .77 x 10^9

=> All the exponents are equal, we can now add and subtract the normally.

=> (3.3 + 2.6 + .77) x 10^9

=> 6.67 x 10^9

=> So the answer to the 2nd question is 6.67 x 10^9

Next question,

=> 8 X 10^4 - 3.4 x 10^4  - 1.2 x 10^3

=> we need to make the exponents equal

=> 8 x 10^4 - 3.4 x 10^4 - .12 x 10^4

=> All the exponents are equal, we can now add and subtract the normally.

=> (8 - 3.4 - .12) x 10^4

=> 4.48 x 10^4

=> So the answer to the 3rd question is 4.48 x 10^4

The solutions to the expressions are:

[tex]4.2 \times 10^6 - 1.2 \times 10^5 - 2.5 \times 10^5[/tex]=[tex]38.3\times 10^5[/tex]

[tex]3.3 \times 10^9 + 2.6 \times 10^9 + 7.7 \times 10^8[/tex] = [tex]6.67\times 10^9[/tex]

[tex]8.0 \times 10^4 -3.4 \times 10^4 - 1.2 \times 10^3[/tex] = [tex]4.48 \times 10^4[/tex]

[tex]4.2 \times 10^6 - 1.2 \times 10^5 - 2.5 \times 10^5[/tex]

Combine like terms:

[tex]4.2 \times 10^6 - (1.2+2.5) \times 10^5[/tex]

[tex]4.2 \times 10^6 - 3.7 \times 10^5[/tex]

[tex]42 \times 10^5 - 3.7 \times 10^5[/tex]

[tex](42-3.7)\times 10^5[/tex]

[tex]38.3\times 10^5[/tex]

[tex]3.3 \times 10^9 + 2.6 \times 10^9 + 7.7 \times 10^8[/tex]

Convert all terms with same power:

[tex]3.3 \times 10^9 + 2.6 \times 10^9 + 0.77 \times 10^9[/tex]

[tex](3.3+2.6+0.77) \times 10^9[/tex]

[tex]6.67\times 10^9[/tex]

[tex]8.0 \times 10^4 -3.4 \times 10^4 - 1.2 \times 10^3[/tex]

[tex]8.0 \times 10^4 - 3.4 \times 10^4 - 0.12 \times 10^4[/tex]

[tex](8.0-3.4-0.12) \times 10^4[/tex]

[tex]4.48 \times 10^4[/tex]

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it is 4km from Martina house to the nearest mailbox. how far is it in meters?

Answers

Answer:

4,000

Step-by-step explanation:

1 kilo = 1,000 meters.

The average age of cars owned by residents of a small city is 6 years with a standard deviation of 2.2 years. A simple random sample of 400 cars is to be selected, and the sample mean age of these cars is to be computed. We know the random variable has approximately a normal distribution because of

Answers

Answer:

The random variable [tex]\bar x[/tex] has approximately a normal distribution because of the central limit theorem.

Step-by-step explanation:

According to the Central Limit Theorem if we have an unknown population with mean μ and standard deviation σ and appropriately huge random samples (n ≥ 30) are selected from the population with replacement, then the sampling distribution of the sample mean will be approximately normally distributed.  

Then, the mean of the sample means is given by,

[tex]\mu_{\bar x}=\mu[/tex]

And the standard deviation of the sample means is given by,

[tex]\sigma_{\bar x}=\frac{\sigma}{\sqrt{n}}[/tex]

Let the random variable X be defined as the age of cars owned by residents of a small city.

It is provided that:

μ = 6 years

σ = 2.2 years

n = 400

As the sample selected is too large, i.e. n = 400 > 30, according to the central limit theorem the sampling distribution of the sample mean ([tex]\bar x[/tex]) will be approximately normally distributed.  

how do you work out 28.4 x 1.92

Answers

Answer:

54.528

Step-by-step explanation:

Which set of whole numbers but not natural numbers

Answers

Answer:

C

Step-by-step explanation:

C is the set with whole numbers as it contains 0 and natural numbers

Help Please I will
Mark brainliest

Answers

Answer:

-2

Step-by-step explanation:

The output of the chart and graph drops by 2 for every input.

help me with this question​

Answers

Answer:

x=5

y=2

w= -5

Step-by-step explanation:

We have that the two matrix are equal, so all corresponding elements are equal.

X-Y=3

From the second row and second column, we have y=2

so x-2=3

x=5

From the third row and the first column, we have w= - 5

Solve : 3X + 3x + 1 + 3x + 2 = 39​

Answers

Step-by-step explanation:

[tex]3x + 3x + 1 + 3x + 2 = 39 \\ 9x + 3 = 39 \\ 9x = 39 - 3 \\ 9x = 36 \\ x = \frac{36}{9} \\ x = 4[/tex]

Answer:

x = 4

Step-by-step explanation:

combine all of the 3x first to get:

9x + 1 + 2 = 39

9x + 3 = 39

subtract 3 from both sides:

9x = 36

divide by 9

x = 4

who is going to win the race?

Answers

Answer:

The correct answer is

Step-by-step explanation:

Red team is going to win the race as they have covered more area than other teams. I am a 100% sure of this answer.Hope this helps....Have a nice day!!!!

Answer:

Red Team

Step-by-step explanation:

Convert 1 3/4 into a improper fraction.

Answers

Answer:

the answer must be 7/4 because

Step-by-step explanation:

1 3/4 4×1+3=7

Answer ASAP, Will give brainliest.

Answers

Answer:

[tex]\huge\boxed{10.4\ units\²}[/tex]

Step-by-step explanation:

Area of circle:

=> [tex]\pi r^2[/tex]

Where r = 2.8

=> [tex](3.14)(2.8)^2[/tex]

=> (3.14)(7.84)

=> 24.6 units²

Area of Triangle:

=> 1/2 (Base)(Height)

=> 1/2 (10)(7)

=> 5 * 7

=> 35 units²

Area of the shaded region:

=> 35 - 24.6

=> 10.4 units²

Question 5 of 10
Which type of unemployment is characterized by a worker looking for a job
when there is no reason that he or she should not find one?
A. Structural unemployment
B. Seasonal unemployment
C. Frictional unemployment
D. Periodic unemployment

Answers

I think the answer has to be C. Frictional unemployment

Determine the sum of the measures of the exterior angles of a convex hexagon (6-sided polygon). Question 1 options: 360° 540° 720° 1,080°

Answers

Answer:

360°

Step-by-step explanation:

The sum of the exterior angles of any polygon = 360°

The sum of the measures of the exterior angles of a convex hexagon will be 360°. Then the correct option is A.

What is a regular hexagon?

The complete polygonal shape of a regular hexagon has six rotational symmetry and six equal angles. Any periodic polygon has symmetrical sides and angles on all vertices.

The external angle of the regular hexagon will be given as,

External angle = 360° / 6

External angle = 60°

Then the sum of the measures of the exterior angles of a convex hexagon will be

⇒ 60° x 6

⇒ 360°

The sum of the measures of the exterior angles of a convex hexagon will be 360°.

Then the correct option is A.

More about the regular hexagon link is given below.

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PLEASE help me with this question. This is really URGENT

Answers

Changing the exponent by 1/2 ( going from x to 1/2x)

This does not change the y-intercept.

It does sharpen the curve, which means the y value does not increase as quickly when x is increased.

THe 3rd choice is correct.

Proof: make x=2

Y = 3^2 = 9

Y = 3^1/2(2) = 3^1 = 3

You can see y is smaller with the 1/2 included.

Write each expression using a positive exponent. ("/" means division)("^" means to the power of) 9^-4

Answers

Answer:

Step-by-step explanation:

[tex]9^{-4}[/tex]

=[tex]\frac{1}{9^{4} }[/tex]                   ∴     [tex]x^{-n} = \frac{1}{x^{n} }[/tex]

=[tex]\frac{1}{9*9*9*9}[/tex]

=[tex]\frac{1}{6561}[/tex]

Please answer question now

Answers

Answer:

3

Step-by-step explanation:

2 tangents of a circle drawn from an external point are said to be congruent, according to the two-tangents theorem. Thus:

MN = ML (both tangents from external point M)

ML = 6 - KL

KL = KJ (tangents from point K)

PQ = QJ = 1 (tangents from point Q)

Therefore, KJ = 4 - 1 = 3

Since kJ = KL = 3,

ML = 6 - KL = 6 - 3

ML = MN = 3

sorry for the really bad quality!!

Answers

Answer:

B

Step-by-step explanation:

f(x) = x+5 when x>0. f(5)=10

B hope this helps you

find whether the following mathematical sentence are constant or variable . 'm' represent the whole numbers between 5 and 7​

Answers

Answer:

Constant

Step-by-step explanation:

Whole numbers are numbers like 1,2,3 and 4.

1.1,2.3 and Pi arent't whole numbers. Fractions like 3/4 and 5/3 aren't whole numbers.

The whole numbers starting from 5 to 7 are:

● 5, 6 and 7

You can see that we have only one whole number between 5 and 7 wich is 6.

So m has only one value (m=6).

=> m is a constant

what is the value of the angle ?

Answers

Answer:

47°

Step-by-step explanation:

The exterior angle of a triangle is equal to the sum of the 2 opposite interior angles

124° is an exterior angle , thus

77 + ? = 124 ( subtract 77 from both sides )

? = 47°

What is the value of 4² - 2(3·5+1)? plz help, will mark brainliest A. 8 B. 1 C. -16 D. -21

Answers

Answer:

Hey there!

4^2-2(3(5)+1)

16-2(15+1)

16-2(16)

-16

C is correct.

Let me know if this helps :)

Answer:

[tex] \boxed{ \mathsf{ \boxed{ \purple{ \bold{{ - 16}}}}}}[/tex]

Step-by-step explanation:

[tex] \mathsf{ {4}^{2} - 2(3 \times 5 + 1)}[/tex]

Evaluate the power

⇒[tex] \mathsf{16 - 2(3 \times 5 + 1)}[/tex]

Multiply the numbers

⇒[tex] \mathsf{16 - 2(15 + 1)}[/tex]

Calculate the sum

⇒[tex] \mathsf{16 - 2 \times 16}[/tex]

Multiply the numbers

⇒[tex] \mathsf{16 - 32}[/tex]

Calculate

⇒[tex] \mathsf{ - 16}[/tex]

Hope I helped!

Best regards!

If the equation of a line is y = -2/3x + 1/3, what is the slope and y-intercept?

Answers

Step-by-step explanation:

Hey, there!!!

Let me explain you very simply,

The equation is;

y= -2/3 x +1/3

Now, we know the equation of a st.line in slope intercept form is,

y= m.x + c

now, comparing the given equation with y= m.x + c. we get,

m= -2/3

and y-intercept = 1/3.

Hope it helps...

Find the surface area of the composite figure

Answers

Answer:

144 cm²

Step-by-step explanation:

This figure is formed by rectangles and triangles, so we need to find the surface area of they and add all to have the surface area of the figure:

area of the rectangles:

4×3 = 12, and there are two of these rectangles

6×3 = 18, and there are just one of that

4×6 = 24, and there are two of these

5×3 = 15, and there are two of these

Now the area of a triangle:

6×4/2 = 12, and there are two of these

12×2 + 18 + 24×2 + 15×2 + 12×2 = 144 cm²

A laundry basket contains 18 blue socks and 24 black socks. What is the probability of randomly picking 2 black socks, with replacement, from the basket?

Answers

Answer:

144/441

Step-by-step explanation:

There are 18+24=42 total socks

There are 24 black socks

So the probability is (24/42)*(24/42)=12/21 * 12/21 = 144/441

Answer:

189

Step-by-step explanation:

PLEASE ANSWER QUICKLY ASAP
ANSWER QUESTION A AND B​

Answers

Answer:

a) [tex]a+b+c=\begin{pmatrix}-2\\-3\end{pmatrix}[/tex]

b) (i) [tex]a+2c=\begin{pmatrix}-4\\2\end{pmatrix}[/tex]

   (ii) [tex]k=2[/tex]

Step-by-step explanation:

It is given that,

[tex]a=\begin{pmatrix}4\\-10\end{pmatrix},b=\begin{pmatrix}-2\\1\end{pmatrix},c=\begin{pmatrix}-4\\6\end{pmatrix}[/tex]

a)

We need to find the value of a+b+c.

[tex]a+b+c=\begin{pmatrix}4\\-10\end{pmatrix}+\begin{pmatrix}-2\\1\end{pmatrix}+\begin{pmatrix}-4\\6\end{pmatrix}[/tex]

[tex]a+b+c=\begin{pmatrix}4+(-2)+(-4)\\-10+1+6\end{pmatrix}[/tex]

[tex]a+b+c=\begin{pmatrix}-2\\-3\end{pmatrix}[/tex]

b)

(i) We need to find the value of a+2c.

[tex]a+2c=\begin{pmatrix}4\\-10\end{pmatrix}+2\begin{pmatrix}-4\\6\end{pmatrix}[/tex]

[tex]a+2c=\begin{pmatrix}4\\-10\end{pmatrix}+\begin{pmatrix}-8\\12\end{pmatrix}[/tex]

[tex]a+2c=\begin{pmatrix}4+(-8)\\-10+12\end{pmatrix}[/tex]

[tex]a+2c=\begin{pmatrix}-4\\2\end{pmatrix}[/tex]

(ii) It is given that a+2c=kb, where k is an integer. We need to find the value of k.

[tex]a+2c=k\begin{pmatrix}-2\\1\end{pmatrix}[/tex]

[tex]\begin{pmatrix}-4\\2\end{pmatrix}=\begin{pmatrix}-2k\\k\end{pmatrix}[/tex]

On comparing both sides, we get

[tex]k=2[/tex]

2. Give an example of a rational number that is not a whole number.

Answers

This are a few of Rational numbers are not whole numbers: 8,−3,32,7−5.

Step-by-step explanation: Hope this helps

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