a² + b² + ab = 7
b² + c² + bc = 21
a² + c² + ac = 28 ab + bc + ac = ?
Answers
Answer:
ab+bc+ac = 7+21 + 28 =56
so the answer is 56
Observe that
[tex]a^2 + b^2 + ab = 7 \iff a^2 + b^2 - 2\cos(120^\circ) = \left(\sqrt 7\right)^2[/tex]
[tex]b^2 + c^2 + bc = 21 \iff b^2 + c^2 - 2\cos(120^\circ) = \left(\sqrt{21}\right)^2[/tex]
[tex]a^2 + c^2 + ac = 28 \iff a^2 + c^2 - 2\cos(120^\circ) = \left(\sqrt{28}\right)^2[/tex]
Drawing a comparison to the law of cosines, we see the first equation defines a triangle with sides [tex]a[/tex], [tex]b[/tex], and [tex]\sqrt 7[/tex]; the second equation defines one with sides [tex]b[/tex], [tex]c[/tex], and [tex]\sqrt{21}[/tex]; and the third equation defines another one with sides [tex]a[/tex], [tex]c[/tex], and [tex]\sqrt{28}[/tex]. We can then join these triangles at a point D to form a new triangle ABC with sides [tex]\sqrt7,\sqrt{21},\sqrt{28}[/tex]. (See attached sketch)
Now, the area of ABC is the sum of the areas of ABD, BCD, and ACD. The area of any of these triangles is equal to half the area of a parallelogram spanned by the sides involving the vertex D. The area of a parallelogram with adjacent sides [tex]x[/tex] and [tex]y[/tex] and with angle [tex]\theta[/tex] between them is [tex]ab\sin(\theta)[/tex].
For example, triangle ABD has area
[tex]\mathrm{area}_{\Delta ABD} = \dfrac12 \times ab \sin(120^\circ)[/tex]
Then the total area of triangle ABC is
[tex]\mathrm{area}_{\Delta ABC} = \dfrac12 \sin(120^\circ) (ab + ac + bc)[/tex]
We use Heron's formula to find the area of ABC. If [tex]s[/tex] is its semiperimeter, i.e.
[tex]s = \dfrac{\sqrt7 +\sqrt{21} + \sqrt{28}}2[/tex]
then, with a lot of algebraic simplification,
[tex]\mathrm{area}_{\Delta ABC} = \sqrt{s (s-\sqrt7) (s - \sqrt{21}) (s - \sqrt{28})} = \dfrac{7\sqrt3}2[/tex]
Finally, we find
[tex]\dfrac{7\sqrt3}2 = \dfrac12 \sin(120^\circ) (ab + ac + bc) \implies ab + ac + bc = \dfrac{\frac{7\sqrt3}2}{\frac12\times\frac{\sqrt3}2} = \boxed{14}[/tex]
Related Questions
What is the slope of the line shown below?
A. 2/7
B.-7/2
C.-2/7
D. 7/2
Answers
(WORK SHOWN BELOW)
Answer:
-2/7
Step-by-step explanation:
We can use the slope formula
m = ( y2-y1)/(x2-x1)
= ( 1-3)/( 3 - -4)
= (1-3)/( 3+4)
= -2/7
Find y please help !!!
Answers
Answer:
20°
Step-by-step explanation:
take the sum of 3y + 10 and y and equal it to 90° that creates an equation making it easier for you to continue
Answer:
Y = 20°let's assume the opposite angle of Y to be X
angle Y = angle X ( vertically opposite angles)
3y + 10 + X + 90° = 180° ( forming linear pair)
3y + X + 100 = 180°
X + 3y = 80° ----(1)
Y + 3y = 80°
4y = 80°
y = 20°
Tim earns 96pounds for 16 hours. Tim earns 'time and a half' for overtime. he works 4 hours of overtime in addition to his normal 16 hours. how much does he earn altogether
Answers
find hourly rate:
96 / 16 = 6 pounds per hour
6 x 1.5 = 9 pounds per hour for overtime.
9 x 4 = 36 pounds
96 + 36 = 132 pounds total
196/16 = 6 per hr
overtime = 6*1.5=9
96 + (9*4) = 132
in case of severe pathologic hypersecretory conditions a physician may order ZantacR up to 6 g/day if the patient is to be given 1.5 g/day divided into four doses what is the amount to administer per dose?
Answers
Step-by-step explanation:
sorry sorry ^$£%£$¥#^÷£=₩€%¥=£=;÷¥÷¥9=
find the midpoint A and B where A has a coordinates (2, 7) and B has coordinates (6,3)
Answers
Answer:
(2+6)/2= 4 (x-coordinate of midpoint)
(7+3)/2= 5(y=coordinate of midpoint)
Answer:
Hope it will help you:)
Step-by-step explanation:
Solution:
here,
A(2,7)-([tex]x_{1,}y_{1[/tex])
B(6,3)-([tex]x_{2},y_{2[/tex])
Now using midpoint formula,
midpoint of ab=(x1 + x2)/2, (y1 + y2)/2
=(2+6)/2,(7+3)/2
=(8/2,10/2)
=(4,5)
The midpoint of AB is(4,5).
A shop advertises a 24% off sale. The coat sold for $258 fins the decrease in price and the sale price
Answers
Answer:
339.47
Step-by-step explanation:
100 - 24 = 76
258 = 76 percent
3.39473684211 = 1 percent
339.47 = 100 percent
Answer:
The decrease in price is $61.92
The sale price is $196.08
Step-by-step explanation:
24% × 258 = 61.92
258 decrease 24% =
258 × (1 - 24%) = 258 × (1 - 0.24) = 196.08
Cylinders A and B are congruent. Cylinder A has a volume of (27pi cm^3)? and a height of 3 cm. What is the diameter of Cylinder B?
A) 3 cm
B) 6 cm
0 9 cm
D) 12 cm
E) 27 cm
Answers
If P(n) and Q(n) are polynomials of degree j and k, respectively, then the series
Infinite
Σ P(n)/Q(n)
n=1
converges if j < k − 1 and diverges if j ≥ k – 1.
Use the polynomial test given above to determine whether the series converges or diverges.
Infinite
Σ 1/(n)^8 +7
n=1
O converges
Odiverges
Answers
Answer:
converges
Step-by-step explanation:
well the two polynomials in the series are 1 and n^8 (I'm assuming the +7 is not in the decimal but it seems to not matter). The degree of the polynomial 1 is 0 which can be represented by 1x^0. The second polynomial in the denominator has a degree of 8. So j = 0 and k = 8. Since 0 < (8-1)
0 < 7 the series converges
two sides and an angle are given below. determine whether the given information results in one triangle, two triangles, or no triangle at all. solve any resulting triangle(s). b = 8, c= 7, b = 170°
Answers
Answer:
A. single triangle. C = 8.74°, A = 1.26°, a = 1.01
Step-by-step explanation:
When two sides and an angle are given, the possibility of two (or zero) triangles exists only when the given angle is opposite the shorter of the two given sides. That is not the case here, so the given measures define one unique triangle.
Law of SinesThe law of sines tells us the sides and angles have the relation ...
sin(A)/a = sin(B)/b = sin(C)/c
We can use this first to find angle C:
sin(C) = c/b·sin(B)
C = arcsin(c/b·sin(B)) = arcsin(7/8·sin(170°)) ≈ 8.7394°
∠C ≈ 8.74°
Remaining measuresNow that we know two angles, we can find the third:
A = 180° -B -C = 180° -170° -8.74° = 1.26°
∠A = 1.26°
Using the law of sines again, we can find the measure of side 'a'.
a = b·sin(A)/sin(B) = 8·sin(1.26°)/sin(170°) ≈ 1.01346
The measure of segment 'a' is about 1.01 units.
__
Additional comment
If 'a', 'b', and angle A are given, there will be zero triangles if b/a·sin(A) > 1. If b/a·sin(A) < 1 and b > a, there will be two (2) triangles. Otherwise, as here, there will be one unique triangle.
The dot plot shows the number of books lent by a school library during a 10-day period.
What was the mean absolute deviation of the number of books?
F. 0
G.
H.
J.
1.04
1.96
..
23 24 25 26 27 28 29 30 31 32 33
2.19
Answers
The mean absolute deviation of the number of books is 1.84
How to determine the mean absolute deviation?The dot plot of the number of books is in the attached figure.
From the figure, we have:
x f
1 1
2 2
3 2
4 3
5 1
6 2
7 3
8 1
Start by calculating the mean using:
[tex]\bar x= \frac{\sum fx}{\sum f}[/tex]
So, we have:
[tex]\bar x= \frac{1 * 1 + 2 * 2 + 2 * 3 + 3 * 4 + 1 * 5 + 2 * 6 + 3 *7 + 1 * 8}{1 +2+2+3+1+2+3+1}[/tex]
Evaluate the sum and products
[tex]\bar x= \frac{69}{15}[/tex]
Divide
[tex]\bar x= 4.6[/tex]
The mean absolute deviation is then calculated as:
[tex]|\bar x| = \frac{\sum f|x - \bar x|}{\sum f}[/tex]
So, we have:
[tex]|\bar x|= \frac{1 * |1 -4.6|+ 2 * |2 -4.6| + 2 * |3 -4.6|+ 3 * |4 -4.6|+ 1 *| 5 -4.6|+ 2 * |6 -4.6|+ 3 *|7 -4.6|+ 1 * |8-4.6|}{1 +2+2+3+1+2+3+1}[/tex]
Evaluate the absolute difference
[tex]|\bar x|= \frac{1 * 3.6+ 2 * 2.6 + 2 * 1.6+ 3 * 0.6+ 1 *0.4+ 2 * 1.4+ 3 *2.4+ 1 * 3.4}{15}[/tex]
Evaluate the sum of products
[tex]|\bar x|= \frac{27.6}{15}[/tex]
Divide
[tex]|\bar x|= 1.84[/tex]
Hence, the mean absolute deviation of the number of books is 1.84
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A menu has five choices of appetizers
Answers
The number of the meals possible is 350.
The complete question is given below:-
A menu has 5 choices of appetizers, ten main courses, and seven desserts. How many meals are possible?
What is the combination?The arrangement of the different things or numbers in a number of ways is called the combination.
Given that:-
A menu has 5 choices of appetizers, ten main courses, and seven desserts.The number of the combination of the meals will be calculated as:-
N = 5 x 10 x 7
N = 350
Therefore the number of the meals possible is 350.
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Andres rolls a standard six-sided die, numbered from 1 to 6. Which word or phrase
describes the probability that he will roll a number greater than or equal to 1?
Answers
I don't know what the word or phrase is, but with the parameters you've given, 100%
Determine the distance between two points. (9,-9) and (-6,-7)
Answers
Which expressions are equivalent to 9b?
Choose all answers that apply
A. b+2(b+2b)
B. 3b+b
C. 2(2b)
Answers
Answer:
A. b+2(b+2b)
b + 2b + 4b = 7b
B. 3b + b = 4b
C. 2(2b) = 4b
None of them are equal to 9b
Answer:
[tex]\fbox {None}[/tex]
Step-by-step explanation:
A
b + 2(b + 2b)b + 2(b) + 2(2b)b + 2b + 4b7bB
3b + b4bC
2(2b)4bfind the missing number in ?/4 = 27/36
Answers
[tex]\text{First I would recommend replacing the question mark with x}\\\text{We have two ratios, }\\\text{and we need to solve that hard-looking equation}\\\text{in terms of x}[/tex]
[tex]\rule{300}{1.7}[/tex]
[tex]\text{We can multiply x times 36:: 36x}\\\text{We can multiply 4 times 27:: 108}[/tex]
[tex]\rule{300}{1.7}[/tex]
[tex]\text{Now it's easier to solve for x:: 36x=108; x=3}\\\text{ (we divided by 36 on both sides of the = sign)}[/tex]
[tex]\rule{300}{1.7}[/tex]
[tex]\text{The missing number is 3}[/tex]
The ratio of the number of laps Andy swam to the number of laps Ben swam
on the first day of a swimming lesson was 5: 6. The ratio of the number of
laps Andy swam to the number of laps Ben swam on the second day of the
swimming lesson was 9: 5. If Ben swam 33 laps on both days, how many laps
did Andy swim on the second day of the swimming lesson?
Answers
Answer:
10
Step-by-step explanation:
Michael designed an activity plan for the next week he determined that they could run at 6 miles per hour and walk at 3 mph if Michael dedicates 12 hours in the week to travel a total distance of 48 miles how many hours does Michael plan on running and walking
Answers
Answer:
Run 4 hours, Walk 8 hours.
Step-by-step explanation:
Let R be the running time
Let W be the walking time
Distance = Speed x Time
48 = 6R + 3W (equation 1)
12 = R + W (equation 2)
We will use elimination method to solve for these simulteanous equations.
Multiply Equation 2 by 3.
12x3 = 3(R+W)
36 = 3R + 3W (equation 3)
now subtract equation 3 from equation 1.
48-36 = 6R - 3R + 3W - 3W
12 = 3R
R = 12/3
= 4hours
now Substitute R into equation 2.
12 = 4 + W
W = 12 - 4
= 8
Therefore Michael plan to run for 4 hours and walk for 8 hours.
Solve: 8 + x/3 = 1/6 (x-6) -1
A. x = 60
B. x = -60
C. x = -36
D. There are infinitely many solutions
Answers
Answer: B -60
Step-by-step explanation: When you plug in -60 into the equation it all equals out into -12 = -12, which is true. All of the other solutions don't work.
Answer:
B. x = -60
Step-by-step explanation:
8 + x/3 = 1/6 (x-6) - 1
Multiply both sides by 6.
48 + 2x = x - 6 - 6
x = -12 - 48
x = -60
can I get a help please
Answers
Answer:
middle graph
Step-by-step explanation:
Soluton
The second (middle ) graph is the only one that works.
First of all when you simplicity the right, you get y = x^2 - 1). That means that x does not go through 0,0. If you put x = 0 into x^ - 1 = 0, you get - 1. So on that basis alone both the first and third graphs are incorrect.Second, both xs in the factors are plus, so x^2 is plus, which means the graph opens upward.Which expressions are completely factored?
30a^6-24a^2=3a^2(10a^4-8)
Answers
The factorisation of the given algebraic expression is [tex]6a^{2} (5a^{4}-4 )[/tex].
The given expression is [tex]30a^{6} -24a^{2}[/tex].
We need to factorise the given expression.
What are the factors?Each of these numbers and expressions is referred to as a factor of algebraic expressions if it is possible to express algebraic expressions as the product of numbers, algebraic variables, or algebraic expressions.
Now, [tex]30a^{6} -24a^{2}=6a^{2} (5a^{4}-4 )[/tex]
Therefore, the factorisation of the given algebraic expression is [tex]6a^{2} (5a^{4}-4 )[/tex].
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You deposit $400 in an account earning 2% interest compounded annually. How much will you have in the account in 20 years?
Answers
Answer:
Approximately $594.38
Step-by-step explanation:
Use the formula: y = a(1 + r)^t
a is the initial amount
r is the percent of interest in decimal form
t is the time in years
y is the money after t years
Substitute the values given in the problem into the equation:
400(1+0.02)^20
Use a calculator or solve manually
Around 594.38
How can I simplify this equation 2y+3(x-4x)
Answers
Answer:
2y - 9x
Step-by-step explanation:
2y + 3 ( x - 4x )
First, solve the brackets.
2y + 3x - 12x
Combine like terms.
2y - 9x
Answer:
[tex]\sf 2y-9x[/tex]
Step-by-step explanation:
Hi There Student! Let me help you out on this question.
________________________________________________________
SimplifyingIn this problem, we are given an expression [tex]\longmapsto\pmb{2y+3(x-4x)}[/tex], and asked to simplify it.
↪
First, we can perform the operation inside the parentheses, x-4x:
[tex]\longmapsto\sf 2y+3(-3x)}[/tex].
Now we can multiply 3 times -3x:
[tex]\longmapsto\sf 2y-9x[/tex]
And that is our final answer, because 2y and -9x are not like terms.
Hope that this helped! Have a good day ahead.
Best Wishes!
[tex]\star\bigstar\overline{\overline{\underline{\underline{\textsf {Reach far. Aim high. Dream big.}}}}}\bigstar\star[/tex]
◆◈-Greetings!-◈◆
-______________________________
jessica has 4/8 of a bottle of roitussun on hand the pharmacist instructs to reduce it by 1/2 how much robitussun does the pharmacist need to prepare the prescription
Answers
Answer:
1/4
Step-by-step explanation:
4/8 = 1/2
1/2 x 1/2 = 1/4
classify the equation 9(a-4)+3(2a+5)=7(3a-4)-6a+7
Answers
Answer:
0 = 0 thats my answer
Step-by-step explanation:
Fill in the blank to make the tw
7
9
||
0
54
X
Answers
Answer:
lol
79*540=lol haha
Step-by-step explanation:
then lol lala lol hahahaha hahaha ten another big lol get it lollalol
How to translate a graph of y= absolute value of x to obtain the graph of y= absolute value of x-6
Answers
Answer: Translate the graph of y=|x| 6 units to the right.
Put the equation y+x^2-10+16 in the form y=(x-h)^2+k
Answers
Answer:
Step-by-step explanation:
hello :
y=x²-10x+16 in the form y=(x-h)²+k
y= x²-2(5)(x)+16
y = x²-2(5)(x)+5²-9
y= (x-5)²-9 when h=5 and k = -9
ON ECRIT SUR LES DUN DE EQUILIBRE CHACUNE DES LETTRES AMURES
Answers
Answer:
oh.
Step-by-step explanation:
A boardwalk game of chance costs $1 to play. You have a 25% chance of winning $1 back, a 20% chance of winning $2
(your $1 back, plus an additional $1), and a 10% chance to win $5 (a gain of $4). What is the expected value of playing
the game if you lose your bet 45% of the time?
A. -$1.00
B. -$0.25
C.-$0.15
D. $0.15
Answers
Answer:
the answer is c
Step-by-step explanation:
Which relation below is NOT a function?
A. {(-2, 4), (1,3), (0,4)}
B. {(5,5), (4,4), (3,3) }
C. {(-4,0), (-7,0), (11, 0)}
D. {(1,4), (2,5) (1,7)}
Answers
D has two possible values of y when x = 1 therefore it is NOT a function
