Evaluate Trig Subs Integral w/ e^x = sin∅

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whatlifeforme
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Homework Statement


Use a trigonometric substitution to evaluate the integral.


Homework Equations


[itex]\int e^x\,dx[/itex] [itex]/\sqrt{1-e^2x}[/itex]


The Attempt at a Solution


e^x = sin∅
x=lnsin∅
dx=cos∅/sin∅


[itex]\frac{sin∅*cos∅}{sin∅*\sqrt{1-(sin∅)^2}}[/itex]





[itex]\int sin∅cos∅<br /> /<br /> sin∅(cos∅)\,d∅[/itex]



[itex]\int \,d∅ = ∅[/itex]

e^x = sin∅
∅ = arcsin(e^x)

answer:
∅ + C
arcsin(e^x) + c
 
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hi whatlifeforme! :smile:
whatlifeforme said:
sin∅/sqrt(1-(sin∅)^2)



[itex]\int sin∅cos∅<br /> /<br /> sin∅(cos∅)^2\,dx[/itex]

nooo :redface:

you forgot the sqrt :wink:

(btw it's easier to say ex = sinθ, so exdx = cosθdθ)
 
tiny-tim said:
hi whatlifeforme! :smile:


nooo :redface:

you forgot the sqrt :wink:

(btw it's easier to say ex = sinθ, so exdx = cosθdθ)

so it should be

[itex]\int sin∅cos∅ <br /> / <br /> sin∅(cos∅)\,dx[/itex]
 
whatlifeforme said:
so it should be

[itex]\int sin∅cos∅ <br /> / <br /> sin∅(cos∅)\,dx[/itex]
thus,[itex]\int 1\,d∅[/itex]

e^x = sin∅
∅ = arcsin(e^x)

answer: arcsin(e^x) + c
 
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tiny-tim said:
yup! :biggrin:

(except of course that integral should have been ∫ 1 dθ :wink:)

ooopss. sry fixed.