A)

B)

how to solve these

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- Nov 11th 2010, 02:09 PMtransgalactictrigonometric equation
A)

B)

how to solve these - Nov 11th 2010, 02:20 PMpickslides
- Nov 13th 2010, 06:28 AMtransgalactic
what is the integral of 1/(cos2y+1)

?

regarding A)

i put v=cosy

- Nov 17th 2010, 02:01 AMtransgalactic
how to solve A

- Nov 17th 2010, 03:43 AMAckbeet
For (A), the substitution renders the equation linear.

- Nov 17th 2010, 04:02 AMtransgalactic
from this substitution i got

by rearanging i got

u'/u +2u=(sin x)^2

what to do now? - Nov 17th 2010, 05:48 AMAckbeet
You did the substitution incorrectly. u = sin(y). sin(x) remains as is.

- Nov 17th 2010, 07:44 AMtransgalactic
i got

u'+2ucosx=-(sin x)^2

i dont know how to solve the right side integral - Nov 17th 2010, 08:21 AMAckbeet
Original DE:

Substitution: Then

Plugging into the DE yields

I think you forgot to distribute the cosine everywhere. So, propagate these changes: what do you get? - Nov 18th 2010, 11:57 AMtransgalactic
on the left side i get cos x (sin x)^2 e^{2sinx}

i dont know how to solve this integral - Nov 18th 2010, 12:01 PMAckbeet
Substitute v = sin(x). Then you'll need by parts twice.

- Nov 18th 2010, 12:41 PMTheCoffeeMachine
- Nov 18th 2010, 12:42 PMtransgalactic
thanks :)

- Nov 18th 2010, 01:18 PMAckbeet
So, did you finish?

- Nov 18th 2010, 01:25 PMtransgalactic
yes

:)

i solved just like you said it went perfect