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I'm lost, can someone tell me how to do this?
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I'm lost, can someone tell me how to do this?

I got to
cosx/(sinx/cosx) = cosx*(cosx/sinx) = cos^2x/sinx = 1-sin^2x/sinx ???
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>>39820
Dude, that's bait. It's not an equality.
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=> cos*sin = (1-cos)(sin/cos)
=> cos = (1-cos)/cos
=> cos^2 =(1-cos)

so it is only true for all x if (1-cos) had been (1-sin^2)
unless you want to solve it for a specific x value
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>>39820
>>39833
cosx = -0.5 +or- (root 5)/2
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>>39837
which has solution x = 0.904
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File: Capture.png (15 KB, 337x203) Image search: [iqdb] [SauceNao] [Google]
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>>39833
>>39826
The question asked for which of the 4 isn't an identity, and the textbook answer is b.
So either this is an identity or the textbook went full retard like 1/3 of the time.
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>>39850
>facepalm.jpg

The left side should be [ (1 - cos x) / cos x ] / tan x . That top line belongs to d, not c.
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>>39861
well shit
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>>39861
then it's actually easy to see:
multiply by (sin x tan x)/(1-cos x) and you obtain:

sin x / cos x = tan x
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>>39937
i think the issue here was he read the problem wrong. its pretty obvious how b. isnt an identity and the rest are.