#How do I integrate this?

25 messages · Page 1 of 1 (latest)

mental mantle
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I tried to simplify the equation to -1 +2/(1-sin(x))

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can someone tell me how to integrate this?

swift nest
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Actually wait no

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$$\frac{1+sinx}{1-sinx} = -\frac{1+sinx}{sinx-1} = -\frac{(sinx-1)+2}{sinx-1} = -1-\frac{2}{sinx-1}$$

half baneBOT
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Arizus

shut anvil
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Can you not multiply the top and bottom by (1+sinx)?

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Resulting in (1+sinx)^2/cos^2x

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Which can be simplified into (1+2sinx+sin^2x)/cos^2x

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Further simplified into sec^2x+2tanxsecx+tan^2x

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then use trig IDs to write 2sec^2x+2tanxsecx+x
Then integrate from there
Wait is my method wrong?

midnight lion
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it does look like a u sub q ngl

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i think all that trig longs things out

swift nest
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The sub probably involves tan

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Cuz i think you can get a sec² and a tan and then do it by parts

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Ah i think i see

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sinx-1
= 2sin(x/2)cos(x/2)-sin²(x/2)-cos²(x/2)
= 2tan(x/2)/sec²(x/2)-1/sec²(x/2)-tan²(x/2)/sec²(x/2)
= -(tan²(x/2) -2tan(x/2)+1)/sec²(x/2)
= -(tan(x/2)-1)²/sec²(x/2)

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So -2/(sinx-1) = sec²(x/2)/(tan(x/2)-1)²

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Then u can use the sub u = tan(x/2)-1

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And everything cancels cuz du/dx = sec²(x/2)/2 so dx = 2/sec²(x/2) and then the sec²(x/2) cancels

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So u just get an integral of 1/u²

midnight lion
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whered the x/2 come from

swift nest
dim cove
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1-sinx + 2sinx