The two identities that are important for this equation are:
(sin x)/(cos x) = tan x
(sin x)^2 + (cos x)^2 = 1
I found it easiest to work on the right side of the equation, and figure it in terms of sin x.
cos x / tan x
= cos x / (sin x / cos x)
= cos x * (cos x / sin x)
= (cos x)^2 / sin x
Next, the (cos x)^2 is equal to 1 - (sin x)^2, so substituting, we get:
= (1 - (sin x)^2) / sin x
Add finally, splitting the numerator,
= 1/sin x - (sin x)^2 / sin x
= 1/sin x - sin x
Which is the left side of the equation. This equation is therefore valid for all non-zero values of sin x.
2006-11-26 03:43:29
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answer #1
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answered by Robert R 2
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If sinx isn't one million, then (one million + sinx) / (one million - sinx) = (one million + sinx)^2 / (one million - sin^2 x) = (one million + 2sinx + sin^2 x) / cos^2 x = sec^2 x + 2secx tanx + tan^2 x = 2sec^2 x + 2secx tanx - one million => Integration = 2tanx + 2secx - x + c. Edit: on the grounds that for f (x) = (one million + sinx) / (one million - sinx), sinx + one million could be 0, assuming this is not 0 will provide in basic terms a partly the final option answer. the perfect answer could be obtained with the aid of right here technique. (one million + sinx) / (one million - sinx) = [one million + cos(?/2 - x)] / [one million - cos(?/2 - x)] = 2cos^2 (?/4 - x/2) / 2sin^2 (?/4 - x/2) = cot^2 (?/4 - x/2) = coesc^2 (?/4 - x/2) - one million => fundamental = 2cot(?/4 - x/2) - x + c [notice the version between the two techniques. f(x) is defined for sinx + one million = 0, i.e., x = - ?/2 for which the 1st answer 2tanx + 2secx - x + c isn't defined while the 2d answer 2cot(?/4 - x/2) - x + c is defined.]
2016-10-13 03:40:31
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answer #2
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answered by ? 4
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In one circle [0, 2π[
1/sinx
x ≠ π (180º), since 1/0 does not exist
With identities you have to work with either the left side or the right side, not both. Besides, you do not use =, because it is not an equation, it is an identity, and you just have to prove it. You use ⇒
1/sinx-sinx⇒
(common denominator (sinx))
(1 - sin^2x)/sinx⇒
since
sin^2x + cos^2x =1
then 1 - sin^2x = cos^2x
You substitute that in the identity
(1 - sin^2x)/sinx⇒ cos^2x/sinx
cos^2x/sinx can be also represented by
(cosx*cosx)/sinx
Now, you can do this
cos^2x/sinx ⇒ cosx*(cosx/sinx)
You know that tanx = sinx/cosx, so
tan^-1 x = cosx/sinx
You substitute that in the identity and you get to prove it
cosx*(cosx/sinx) ⇒ cosx*(1/tanx)⇒ cosx/tanx
And there you have it!!!!!!! I hope it helps
2006-11-26 03:48:55
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answer #3
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answered by Anonymous
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RHS
= cosx / tanx
= cosx / (sinx/cosx)
= (cosx)^2 / sinx
= 1-(sinx)^2 / sinx
= (1/sinx) - sinx
= LHS (Proven)
2006-11-26 03:58:22
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answer #4
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answered by Kemmy 6
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Ok. it is easy.
1/sinx-sinx = 1/sinx - sin(squared)x/sinx
=1-sin(squared)x/sinx
=cos(squared)/sinx
=cosx/sinx*cosx
sinx/cosx=tanx, so cosx/sinx=1/tanx
therefore, 1/tanx*cosx=cos/tan
get it?
things you need to know to understand this:
sin(squared)x+cos(squared)x=1
sinx/cosx=tanx
2006-11-26 03:42:41
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answer #5
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answered by Anonymous
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cosx/tanx
=cosx/(sinx/cosx)=cos^2x/sinx
=(1-sin^2x)/sinx
=(1/sinx)-sinx, as required
i hope that this helps
2006-11-26 03:45:34
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answer #6
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answered by Anonymous
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Start with sin^2(x) + cos^2(x) = 1
cos^2(x) = 1 - sin^2(x)
divide both sides by sin(x)
cos^2(x) / sin(x) = 1/sin(x) - sin(x)
cos(x) * cos(x)/sin(x) = 1/sin(x) - sin(x)
cos(x) / tan(x) = 1/sin(x) - sin(x)
{ sin^2(x) means sin(x) squared { sin(x) * sin(x) }, if you're not familiar with the symbols }
2006-11-26 03:33:12
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answer #7
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answered by Scott R 6
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I assume you mean (1/sinx) - sinx = (cosx/tanx)?
2006-11-26 03:30:23
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answer #8
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answered by Cassi 2
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1/s - s = c/t => t/s - ts = c => 1/c - ss/c = c => 1 - ss = cc => 1= ss + cc which is true. so the answer is yes.
2006-11-26 03:38:06
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answer #9
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answered by gjmb1960 7
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Convert cos(x)/tan(x) into sines and cosines and they simplify:
tan(x) = sin(x)/cos(x) cos(x)/tan(x) = cos(x)/(sin(x)/cos(x)) = cos(x)*(cos(x)/sin(x) = (cos(x))^2/sin x
Now convert 1/sin(x) - sin(x) in to one fraction:
LCD is sin(x), sin(x)/1*(sin(x)/sin(x) = sinx^2/sin(x). 1/sin(x) - sin(x)^2/sin(x) = (1 -(sin(x))^2)/sin(x).
Now use the pythagorian Identity and subtract.
(sin(x))^2 + (cos(x))^2 = 1. 1 = (sin(x))^2 + (cos(x))^2. (1 -(sin(x))^2)/sin(x) = ((sin(x))^2 + (cos(x))^2 -(sin(x))^2). (sin(x))^2 -(sin(x))^2 + (cos(x))^2 )/sin(x). (cos(x))^2 )/sin(x)
Now compare.
(cos(x))^2 )/sin(x) = (cos(x))^2 )/sin(x)
Voila it is the same.
QED
2006-11-26 03:44:17
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answer #10
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answered by Edgar Greenberg 5
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