integration problem

Are you sure that's the problem? Ask your teacher about this, cause the answer to what you wrote is

sin(377t - 30) x + C

Rusted but I think it used to be = - Cos(377t-30) + C

No TVP is right.

for you to be right it must be

∫sin(377t+30)dt but it is dx

you forgot that there is a factor conditioned by the multiplier of "t".

Your result is OK for ∫sin(t) dt but not for ∫sin(a*t+b)dt

I'm sorry , I mean int. sin(377t - 30) dt

OK, since you say you have the right answer, take that and differentiate it. See if you get back to here. Pay close attention to the derivative of the argument.

I have the final answer but it is jut a number (limited integration) I have not any formula to differenciat it . (( big problem :) )

Hi voltage,

You must first transform the expression sin(377t-30) to something you can use easier integration methods on.

Start with the general expression:

sin(u - v) = sin(u)Cos(v) - cos(u)sin(v)

Substitute in your expressions (u = 377t and v = 30).

You should then be able to integrate.

Mike

Not necessary

377t-30 = x

differentiate both

... dt = dx

dt = dx/....

subtitute

∫ f(t) dt becomes a simple ∫f'(x) dx

Since it is too obviously a study material, and possibly a homework, I will not solve it totally.

Also since you don't have the formula but the value, the integration seem to be within limits (ie from t = a to t=b)

thanks for all

note:it is not a home work , I just need it to minimize some thing in my "power electronics" course .