1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
blsea [12.9K]
3 years ago
11

Cos4x = 8 cos^4 x - 8 cos^2 x + 1Please help me prove! :D 

Mathematics
1 answer:
sesenic [268]3 years ago
3 0
From cos(2x) = 2cos^2(x) -1

cos(4x) = 2[cos(2x)]^2 -1
= 2[2cos(x) -1]^2 -1
= 2[4cos^2(x) - 4cos(x) + 1] -1
= 8cos^2(x) - 8cos(x) + 1
You might be interested in
3-14 plzzz except #13 20 points!
Marianna [84]
#3: 15

#4: 13.2

#5: 5.44 (curious as to how you guessed 7)

#6: 7

#7: 7.3

#8: 15

#9: You'd round 0.9 to 1 and 3.78 to 4. 4/1 = 4

#10: Round 2.5 to 3. 36/3 = 12

#11: If they want you to round 0.25 down to 0, then 7/0 is undefined. 

#12: 9.5 rounds to 10 142.5 rounds to 143. 143/10 = 14.3

#14: 24.8 cm divided by 175 = approximately 0.1417 cm per year. Round that up to approximately 0.14 per year. 


4 0
3 years ago
What is the value of h when the function is converted to vertex form?
Alenkinab [10]

Answer: H=3

                    ^ I noticed you need help on this one the answer is very simple




7 0
3 years ago
Olivia will attend Blake University this fall. Tuition for one year is $11,350. Olivia plans to earn $1,500 at her work-study jo
g100num [7]

Answer:

4650 add 1500+1800+3400 u get 6700

then you get the tuition cost then subtract it by 6700

your final answer is 4650 dollar

8 0
3 years ago
100 points!! Brainliest if correct!!
Elena-2011 [213]

surface area (S) of a right rectangular solid is:

S = 2*L*W + 2*L*H + 2*W*H (equation 1)

where:

L = length

W = width

H = height

-----

you have:

L = 7

W = a

H = 4

-----

formula becomes:

S = 2*7*a + 2*7*4 + 2*a*4

simplify:

S = 14*a + 56 + 8*a

combine like terms:

S = 22*a + 56

-----

answer is:

S = 22*a + 56 (equation 2)

-----

to prove, substitute any value for a in equation 2:

let a = 15

S = 22*a + 56 (equation 2)

S = 22*15 + 56

S = 330 + 56

S = 386

-----

since a = 15, then W = 15 because W = a

go back to equation 1 and substitute 15 for W:

S = 2*L*W + 2*L*H + 2*W*H (equation 1)

where:

L = length

W = width

H = height

-----

you have:

L = 7

W = 15

H = 4

-----

equation 1 becomes:

S = 2*7*15 + 2*7*4 + 2*15*4

perform indicated operations:

S = 210 + 56 + 120

S = 386

-----

surface area is the same using both equations so:

equations are good.

formula for surface area of right rectangle in terms of a is:

S = 22*a + 56

-----

8 0
3 years ago
Read 2 more answers
Given a circle with measures of (C, d, and r) and a circle with measures of (C', d', and r'), what is r if C C' = 5 and d' = 20?
PtichkaEL [24]

Answer:

The value of radius r  is 50

Step-by-step explanation:

Given as :

The measure of two circles as

Circumference = c                          Circumference = c'                          

Diameter = d                                    Diameter = d'    

Radius = r                                          Radius = r'

And

\frac{c}{c'} = 5

d' = 20

∴  circumference of circle = 2\times \Pi \times r  = \Pi \times d

Or, \frac{c}{c'} = \frac{2\pi r }{\pi d'}

Or,  5 = \frac{2r}{d'}

Or,  5 =  \frac{2r}{20}

∴  2 × r = 5 × 20

I.e       r = 50

Hence The value of radius r  is 50  Answer

7 0
4 years ago
Read 2 more answers
Other questions:
  • The coordinates of the midpoints of GH are M (4,3) and the coordinates of one endpoints are G (5,-6) the coordinates of the othe
    10·1 answer
  • Math help? Its 9th grade math.
    15·2 answers
  • Jack King pays a $496.00 premium annually. This represents 40% of the total premium. The rest of the premium is paid by his empl
    11·1 answer
  • Ricardo has a square hot tub. He wants to build a square pool next to it that is a dilation of the hot tub using a scale factor
    15·2 answers
  • Which is a counterexample to this conjecture?
    14·1 answer
  • In an all boys school, the heights of the student body are normally distributed with a mean of 69 inches and a standard deviatio
    5·1 answer
  • Help me with this plzzz
    5·2 answers
  • Ash recycles 7 plastic bottles every week. Which expression shows the total number of plastic bottles he recycles in w weeks?
    7·1 answer
  • Help on this question
    12·1 answer
  • What is 9 to the 3rd power x 9 to the second power?​
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!