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viva [34]
2 years ago
5

Prove the identity cos(A+B+C)=cosAcosBcosC-cosAsinBsinC-sinAcosBcosC-sinAsinBcosC

Mathematics
1 answer:
blagie [28]2 years ago
4 0
Hello !

cos (a+b) = cos a cos b - sin a sin b
sin (a+b) = sin a cos b + sin b cos a

cos (a+b+c) = cos (a+(b+c))
cos (a+b+c) = cos a cos (b+c) - sin a sin (b+c)
cos (a+b+c) = cos a (cos b cos c - sin b sin c) - sin a (sin b cos c + sin c cos b)
cos (a+b+c)=cos a cos b cos c - cos a sin b sin c - sin a sin b cos c - sin a cos b sin c
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Answer:

60 copies

Step-by-step explanation:

first you take 1/6th of the original 90 copies which is 15 and subtract that from the 90, you are left with 75 copies which is how many they had left at the end of yesterday. then you take 1/5th of the 75 copies that are left which is also 15 and you subtract that from 75 and you get 60. that's why at the end of today there are 60 copies left.

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3 years ago
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Answer:

B

Step-by-step explanation:

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3 years ago
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Toni drives her car 99 mi on the highway on 3 gal of gas. At this rate how many miles can she drive on 11 gal of gas?
Helen [10]

Answer:

333.67 miles

Step-by-step explanation:

She drives her car 91 mi on 3 gal of gas

That’s 91 mi = 3 gal

How many miles can she drive on 11 gal of gas .

Let the mile she can drive by 11 gal of gas be A

At the same rate ,

91 mi = 3 gall

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4 0
2 years ago
Factor each of the following. Remember: It is the reverse of the distributive property and your first step is to find the greate
vaieri [72.5K]
To factor using the reverse of the distributive property, find what common factor the numbers have and what common factor the variables have.

10.

-8x - 16

8 is a factor of both -8 and 16.
The first term has x, but the second term does not, so there is no common variable. The only common factor is 8, or -8.

Factor out a -8:

-8x - 16 = -8(x + 2)

To see if the factorization is correct, multiply the answer using the distributive property. If you get the original expression, then the factorization is correct.

11.

w^2 - 4w

The first term only has a factor of 1. The second term has a 4. There is no common factor between 1 and 4 except for 1, so there is no number you can factor out. The first term has w^2. The second term has w. Both terms have a common factor of w. We can factor out w from both terms.

w^2 - 4w = w(w - 4)

12.

4s + 10rs

4 and 10 have a common factor of 2.
s and rs have a common factor of s.
2 times s is 2s, so the common factor is 2s.
We now factor out 2s

4s + 10rs = 2s(2 + 5r)
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3 years ago
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