Answers
Answer: see proof below
Step-by-step explanation:
Given: A + B + C = π → A + B = π - C
→ B + C = π - A
→ C + A = π - B
→ C = π - (B + C)
Use Sum to Product Identity: cos A + cos B = 2 cos [(A + B)/2] · cos [(A - B)/2]
Use the Sum/Difference Identity: cos (A - B) = cos A · cos B + sin A · sin B
Use the Double Angle Identity: sin 2A = 2 sin A · cos A
Use the Cofunction Identity: cos (π/2 - A) = sin A
Proof LHS → Middle:
[tex]\text{LHS:}\qquad \qquad \cos \bigg(\dfrac{A}{2}\bigg)+\cos \bigg(\dfrac{B}{2}\bigg)+\cos \bigg(\dfrac{C}{2}\bigg)[/tex]
[tex]\text{Sum to Product:}\qquad 2\cos \bigg(\dfrac{\frac{A}{2}+\frac{B}{2}}{2}\bigg)\cdot \cos \bigg(\dfrac{\frac{A}{2}-\frac{B}{2}}{2}\bigg)+\cos \bigg(\dfrac{C}{2}\bigg)\\\\\\.\qquad \qquad \qquad \qquad =2\cos \bigg(\dfrac{A+B}{4}\bigg)\cdot \cos \bigg(\dfrac{A-B}{4}\bigg)+\cos \bigg(\dfrac{C}{2}\bigg)[/tex]
[tex]\text{Given:}\qquad \quad =2\cos \bigg(\dfrac{A+B}{4}\bigg)\cdot \cos \bigg(\dfrac{A-B}{4}\bigg)+\cos \bigg(\dfrac{\pi -(A+B)}{2}\bigg)[/tex]
[tex]\text{Sum/Difference:}\quad =2\cos \bigg(\dfrac{A+B}{4}\bigg)\cdot \cos \bigg(\dfrac{A-B}{4}\bigg)+\sin \bigg(\dfrac{A+B}{2}\bigg)[/tex]
[tex]\text{Double Angle:}\quad =2\cos \bigg(\dfrac{A+B}{4}\bigg)\cdot \cos \bigg(\dfrac{A-B}{4}\bigg)+\sin \bigg(\dfrac{2(A+B)}{2(2)}\bigg)\\\\\\.\qquad \qquad \qquad =2\cos \bigg(\dfrac{A+B}{4}\bigg)\cdot \cos \bigg(\dfrac{A-B}{4}\bigg)+2\sin \bigg(\dfrac{A+B}{4}\bigg)\cdot \cos \bigg(\dfrac{A+B}{4}\bigg)[/tex]
[tex]\text{Factor:}\quad =2\cos \bigg(\dfrac{A+B}{4}\bigg)\bigg[ \cos \bigg(\dfrac{A-B}{4}\bigg)+\sin \bigg(\dfrac{A+B}{4}\bigg)\bigg][/tex]
[tex]\text{Cofunction:}\quad =2\cos \bigg(\dfrac{A+B}{4}\bigg)\bigg[ \cos \bigg(\dfrac{A-B}{4}\bigg)+\cos \bigg(\dfrac{\pi}{2}-\dfrac{A+B}{4}\bigg)\bigg]\\\\\\.\qquad \qquad \qquad =2\cos \bigg(\dfrac{A+B}{4}\bigg)\cdot \cos \bigg(\dfrac{A-B}{4}\bigg)+\cos \bigg(\dfrac{2\pi-(A+B)}{4}\bigg)\bigg][/tex]
[tex]\text{Sum to Product:}\ 2\cos \bigg(\dfrac{A+B}{4}\bigg)\bigg[2 \cos \bigg(\dfrac{2\pi-2B}{2\cdot 4}\bigg)\cdot \cos \bigg(\dfrac{2A-2\pi}{2\cdot 4}\bigg)\bigg]\\\\\\.\qquad \qquad \qquad =4\cos \bigg(\dfrac{A+B}{4}\bigg)\cdot \cos \bigg(\dfrac{\pi-B}{4}\bigg)\cdot \cos \bigg(\dfrac{\pi -A}{4}\bigg)[/tex]
[tex]\text{Given:}\qquad \qquad 4\cos \bigg(\dfrac{\pi -C}{4}\bigg)\cdot \cos \bigg(\dfrac{\pi-B}{4}\bigg)\cdot \cos \bigg(\dfrac{\pi -A}{4}\bigg)\\\\\\.\qquad \qquad \qquad =4\cos \bigg(\dfrac{\pi -A}{4}\bigg)\cdot \cos \bigg(\dfrac{\pi-B}{4}\bigg)\cdot \cos \bigg(\dfrac{\pi -C}{4}\bigg)[/tex]
LHS = Middle [tex]\checkmark[/tex]
Proof Middle → RHS:
[tex]\text{Middle:}\qquad 4\cos \bigg(\dfrac{\pi -A}{4}\bigg)\cdot \cos \bigg(\dfrac{\pi-B}{4}\bigg)\cdot \cos \bigg(\dfrac{\pi -C}{4}\bigg)\\\\\\\text{Given:}\qquad \qquad 4\cos \bigg(\dfrac{B+C}{4}\bigg)\cdot \cos \bigg(\dfrac{C+A}{4}\bigg)\cdot \cos \bigg(\dfrac{A+B}{4}\bigg)\\\\\\.\qquad \qquad \qquad =4\cos \bigg(\dfrac{A+B}{4}\bigg)\cdot \cos \bigg(\dfrac{B+C}{4}\bigg)\cdot \cos \bigg(\dfrac{C+A}{4}\bigg)[/tex]
Middle = RHS [tex]\checkmark[/tex]
Related Questions
Simplify the expression 8+10p-4-7p
Answers
Evaluate the expression for p = –4.
3p2 − 18(–2 − p) =
Answers
Answer:
12
Step-by-step explanation:
p = -4
3p² - 18(-2 - p)
plug in p
3(-4)² - 18(-2 - (-4))
solve the exponent
3(16) - 18(-2 - (-4))
solve within the parentheses
3(16) - 18(-2 + 4)
3(16) - 18(2)
multiply each expression
48 - 36
subtract
12
6x+2y=12 ( solve for y )
How do I show my work on a piece of paper would help a lot :)
Answers
Answer:
y=6-3x
Step-by-step explanation:
factor out common terms 2(3x+y)=12divide both sides by 2
3x+y=[tex]\frac{12}{2}[/tex] simplify 3x+y=6 subtract 3 from both sides
y=6-3x
-1 7/8 + -6 Help, please.
Answers
Describe the 6 ways to transform a function.
Answers
given a right-angled triangle with perimeter 18. The sum of the squares of the three side lengths is 128. What is the area of the triangle ?
Answers
Answer:
9units²
Step-by-step explanation:
A triangle has 3 sides. Let the length of the three sides be a, b, c.
If the perimeter of the triangle is 18, then;
P = a+b+c
a+b+c = 18... 1
If the sum of the squares of the three side lengths is 128, this means;
a²+b²+c² = 128... 2
Since the triangle is also right angled, according to Pythagoras theorem;
c² = a²+b²... 3 (taking c as the hypotenuse)
Substitute equation 3 into 2;
(a²+b²)+c² = 128
c²+c² = 128
2c² = 128
c² = 128/2
c² = 64
c = √64
c = 8
Substituting c = 8 into 1
a+b+c = 18
a+b+8=18
a+b = 10 ...... 3
Substituting c = 8 into 2
a²+b²+c² = 128
a²+b²+8² = 128
a²+b²+64 = 128
a²+b²= 64..... 4
Solve equation 3 and 4 simultaneously;
a+b = 10
a²+b²= 64
From 4; a = 10-b
Substitute a = 10-b into 4;
(10-b)²+b² = 64
100-20b+b²+b² = 64
2b²-20b+100-64 = 0
2b²-20b+36 = 0
Divide through by 2:
b²-10b+18 = 0
b = 10±√10²-4(18)/2
b = 10±√100-72/2
b =( 10±√28)/2
b =(10±√4×7)/2
b = (10±2√7)/2
b = 5±√7
Hence b = 5+√7
If a+ b = 10
a+(5+√7 ) = 10
a = 10-(5+√7)
a = 10-5-√7
a = 5-√7
Area of the triangle A = 1/2 ab
A = 1/2 × (5+√7) × (5-√7)
A = 1/2 × (25-5√7+5√7-7)
A = 1/2 × (25-7)
A = 1/2 × 18
A = 9
Hence the are of the triangle is 9units²
helphelphelphelphelp
Answers
Answer:
Point A
Step-by-step explanation:
Given: KM bisects JKL
Prove: m MKL= 1/2m JKL
please explain
Answers
Start with out given statement:
Line KM bisects <JKL and the reason for that is because it's given.
For statement 2, we know that m<JKM = m<MKL
because of the definition of an angle bisector.
For statement 3, we can use the angle addition
postulate to get m<JKM + m<MKL = m<JKL.
For statement 4, we use substitution from
the info in statement 2 to get m<MKL + m<MKL = m<JKL.
For statement 5, we simplify to get 2(m < KML) = m<JKL.
For statement 5, we use the division property of equality.
All the reasons are underlined.
Find a general term a, for the sequence whose first four terms are given.
1 /1,1/4,1/9,1/16
Answers
Answer:
an = 1/n^2
Step-by-step explanation:
We notice that the denominators are the squares of successive integers. The general term will be ...
[tex]\boxed{a_n=\dfrac{1}{n^2}}[/tex]
You want to buy a new hat that costs $9.20 on the price tag. How much
will you pay at the register if there is an 8.5% tax? Round to the nearest
cent. *
Answers
Answer:
$9.98 :)
Step-by-step explanation:
just multiply the tax (0.085) by the price ($9.20) then add the initial price ($9.20) to that.
Beach Bicycles sells two-seater bicycles. Its markup rate is 68%. Which equation represents the new price for a bicycle, y, given an original price, x?
Answers
Answer:
y = 1.68x
Step-by-step explanation:
The markup rate of a product or service refers to how higher the selling price is than the total production cost. In this case, this company doesn't produce the bikes, instead it purchases them from a wholesaler, distributor or even the factory, and then resells them in order to make a profit.
E.g. Beach Bicycles purchases two-seater bikes at $200 each, and then it will resell them to their customers at 1.68 x $200 = $336. The total markup in this example is $136, which represents $136/$200 = 68% of the purchase price.
X3-6x-16=0 solve by factoring
Answers
Answer:
X = 3 √ 2 ( 3 x + 8 )
Step-by-step explanation:
Lynn and Max are divers. Lynn's depth gauge says she is 43.6 feet deep. Max's depth gauge says that he is 54.2 feet deep. Who is closer to the surface? Write two statements of inequality to describe the situation.
Answers
Answer: Lynn is closer to the surface.
Step-by-step explanation:
Lynn is 43.6 deep meaning -46.3. Max is 54.2 feet meaning that he is -54.2 feet below sea level. so the smaller the number the close it is to 0 (which in this case is the surface) hope this helped
You have taken up gardening for relaxation and have decided to fence in your new
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of fencing is required to completely enclose it. What is the width of the garden?
Answers
Answer:
13 meters
Step-by-step explanation:
Adjacent sides form half the perimeter, so the sum of the unknown side and the given side is 34/2 = 17 meters.
4 meters + width = 17 meters
width = 13 meters . . . . . subtract 4 meters
Alfred and his 4 friends bought 13 1/4 pounds of gummy bears at $1.20 pound . If the cost is divided between alfred and his four friends what would each person pay
Answers
to find the total cost, just multiply 13.25 by $1.20 to get $15.90. to find the cost per person, just divide $15.90 by 5, which results in each person paying $3.18
Steve had 48 chocolates but decided to give 8 chocolates to each of his f coworkers. How many chocolates does Steve have left?
Answers
So if Steve divided 48 chocolates by how many he would give to each co worker he would have 6 workers and 0 chocolates left.
Hope this helped!! :))
Answer: 40 chocolates
Step-by-step explanation:
If she does not make any deposits or withdrawals, what will be the balance in her
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Answers
Answer:
the same as its been for 2 days
Step-by-step explanation:
D
Question 1
(02.03)
Read the following statement: Line segment CD is congruent to line segment XY.
Which of the following is an equivalent statement? (4 points)
Answers
a rectangular piece of metal is 15in longer then it is wide. squares with sides 3in long are cut from the four corners and the flaps are folded upward to form an open box. if the volume of the box is 1092in cubed what were the original dimensions of the piece of metal?
Answers
Step-by-step explanation:
Let x equal the width of the box and x + 15 equal the length of the box. Subtract 6 (the amount cut out) from both of the these to get the following terms: (x+9) and (x-6). These are the length and width of the box respectively. We also know that the height of the box is 3. Plugging these into the formula for the volume of a box gives you:
3(x+9)(x-6)=1092
Expanding this out gives:
3x^2+9x-162=1092
Subtract 1092 from both sides to make the quadratic equation equal zero. Plug the a, b and c coefficients into the quadratic formula (or factor) to find x.
3x^2 +9x-1254 = 0
a = 3 b = 9 c = -1254
I hope this helps :)
Evaluate the following expression. cos315°
Answers
Answer:
[tex]\sqrt{2}/2[/tex]
Step-by-step explanation:
Making a unit circle will be very helpful if you don't already have one. You will use it for years to come.
Which of the following is an equation of the line with slope 2 that passes through the point (-1,-4)
Show complete working format
Answers
Answer:
y = 2x - 2
Step-by-step explanation:
Slope-Intercept Form: y = mx + b
Step 1: Define
Slope m = 2
Random point (-1, -4)
y = 2x + b
Step 2: Find b
-4 = 2(-1) + b
-4 = -2 + b
-2 = b
Step 3: Rewrite linear equation
y = 2x - 2
The volume of a pyramid, V, is calculated using the formula V = 1/3 AH, where A is the area of the base and H is the height of the pyramid.
Rearrange the formula to solve for the base area (A)
Answers
Answer:
A= 3V/H
Step-by-step explanation:
V=1/3 AH
multiply 3 on both sides
3V=AH
divide both sides by H
3V/H=A
The number of fungi on a culture has increased from 800 spores to 1,600 spores in 1 hour. What is the growth factor for
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0.1
1
2
10
Answers
which point is the center of a circle
Answers
Answer:
isnt it called the focus thats what i think
Step-by-step explanation:
What is f(-2) of the function given below? *
f(x) = 3x2 - 4x + 1
Answers
Answer:
f(-2) = 21
Step-by-step explanation:
Step 1: Define
f(x) = 3x² - 4x + 1
f(-2) is x = -2
Step 2: Substitute and Evaluate
f(-2) = 3(-2)² - 4(-2) + 1
f(-2) = 3(4) + 8 + 1
f(-2) = 12 + 9
f(-2) = 21
Find the product -1(-15) . Oh and also -1(-24) pls help
Answers
Answer:
15 and 24
Step-by-step explanation:
distribute the -1 to the -15 amd it will cancel out same for the other
HELP PLS THIS IS IMMEDIATE
Answers
At the fair, Terrell has 47 ride tickets. Each ride on the Ferris wheel costs 6 tickets. After
riding the Ferris wheel as many times as possible, how many tickets will Terrell have left?
Answers
Answer:
Terrell has 5 tickets left.
Step-by-step explanation:
Your school band is selling T-shirts. The group purchased the tees wholesale for $3.00 each. If the team has a 310% markup, what price are they selling the t-shirts for?
Answers
Answer:
$9.10
Step-by-step explanation:
hope this helps buddy
Cans of peas are 3 for $1.29. How much would one can of peas and a bag of chips priced at $2.19 cost all together?
Answers
Answer:
It would be 2.62
Step-by-step explanation: