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sukhopar [10]
3 years ago
7

An electric current, I, in amps, is given by I=cos(wt)+√8sin(wt), where w≠0 is a constant. What are the maximum and minimum valu

es of I
Mathematics
1 answer:
exis [7]3 years ago
4 0
Take the derivative with respect to t
- w \sin(wt) + \sqrt{8} w cos(wt)
the maximum and minimum values occur when the tangent line is zero so we set the derivative to zero
0 = -w \sin(wt) + \sqrt{8} w cos(wt)
divide by w
0 =- \sin(wt) + \sqrt{8} cos(wt)
we add sin(wt) to both sides

\sin(wt)= \sqrt{8} cos(wt)
divide both sides by cos(wt)
\frac{sin(wt)}{cos(wt)}= \sqrt{8}   \\  \\ arctan(tan(wt))=arctan( \sqrt{8} ) \\  \\ wt=arctan(2 \sqrt{2)} OR\\ wt=arctan( { \frac{1}{ \sqrt{2} } )
(wt)=2(n*pi-arctan(2^0.5))
(wt)=2(n*pi+arctan(2^-0.5))
where n is an integer
the absolute max and min will be

I=cos(2n \pi -2arctan( \sqrt{2} ))
since 2npi is just the period of cos
cos(2arctan( \sqrt{2} ))= \frac{-1}{3} 

substituting our second soultion we get
I=cos(2n \pi +2arctan( \frac{1}{ \sqrt{2} } ))
since 2npi is the period
I=cos(2arctan( \frac{1}{ \sqrt{2}} ))= \frac{1}{3}
so the maximum value =\frac{1}{3}
minimum value =- \frac{1}{3}


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For an arithmetic sequence, a35=57. If the common difference is 5. Find a1 and the sum of the first 61 terms.
Flauer [41]

 

\displaystyle\bf\\a_{35}=57\\r=5\\----\\a_1=?\\S_{61}=?\\----\\Solve:\\1)\\a_1=a_{35}-(35-1)\times r=57-34\times 5=57-170=-113\\\boxed{\bf a_1=-113}\\\\

.

\displaystyle\bf\\2)\\A_{61}=a_1+(61-1)\times r=-113+60\times5=-113+300=187\\\\S_{61}=(-113)+(-108)+(-103)+...+(-8)+(-3)+2+7+12+...+187\\\\S_{61}=SA+SB\\\\SA=(-113)+(-108)+(-103)+...+(-8)+(-3)=-(3+8+103+108+113)\\\\n=\frac{113-8}{5}+1=\frac{105}{5}+1=21+1=22~terms\\SA=-\Big( \frac{n(113+3)}{2} \Big)=-\Big( \frac{22\times116}{2} \Big)=-11\times116 =-1276

.

\displaystyle\bf\\SB=2+7+12+...+187\\\\n=\frac{187-2}{5}+1=\frac{185}{5}+1=37+1=38~terms\\\\SB=\frac{n(187+2)}{2}=\frac{38\times189}{2}=19\times189=3591\\\\S_{61}=SA+SB=-1276+3591=2315\\\\\boxed{\bf S_{61}=2315}    

 

 

8 0
2 years ago
Which expression is equivalent to 24 + 20​
Maslowich
24+20=44
4(6+5)=44
the first one
8 0
3 years ago
GUYS PLEASE HELP ME HELP HELP PLEASE PLEASE!!! Simplify and solve for the unknown. Use order of operations as needed. Check your
grandymaker [24]

The solution is B = 43

Step-by-step explanation:

Simplify and solve for the unknown for 5(B + 3) = 4(B - 7) + 2B

  • Simplify each side
  • Add the like terms in each side if need
  • Separate the unknown in one side and the numerical term in the other side to find the value of the unknown

∵ 5(B + 3) = 4(B - 7) + 2B

- Multiply the bracket (B + 3) by 5 in the left hand side and multiply

  the bracket (B - 7) by 4 in the right hand side

∵ 5(B + 3 ) = 5(B) + 5(3) = 5B + 15

∵ 4(B - 7) = 4(B) - 4(7) = 4B - 28

∴ 5B + 15 = 4B - 28 + 2B

- Add the like terms in the right hand side

∵ 4B + 2B = 6B

∴ 5B + 15 = 6B - 28

- Add 28 to both sides

∴ 5B + 43 = 6B

- Subtract 5B from both sides

∴ 43 = B

- Switch the two sides

∴ B = 43

To check the answer substitute the value of B in each side if the two sides are equal then the solution is right

The left hand side

∵ 5(43 + 3) = 5(46) = 230

The right hand side

∵ 4(43 - 7) + 2(43) = 4(36) + 86 = 144 + 86 = 230

∴ L.H.S = R.H.S

∴ The solution B = 43 is right

The solution is B = 43

Learn more:

You can learn more about the solution of an equation in brainly.com/question/11229113

#LearnwithBrainly

7 0
2 years ago
Can you help me with this question?-8(-4x-1)-9x
Contact [7]
First you have to multiply -8 to (-4x-1)
which is, -12x+8
then there is -9x you have to add like terms
-12x-9x+8
-21x+8 is your final answer
4 0
2 years ago
Casey uses some of his savings on batting practice. the cost of renting a batting cage for 1 hour is $6. he rents a cage for 9 h
sammy [17]
It 54 thank you welcome you
5 0
2 years ago
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