Recent content by Attis

the primitive function is the anti-derivative. so cosx becomes sinx and sinx becomes -cosx? s(t)=-cos3t+sin3t + C Now I got it. I´d gotten confused between the derivative and the anti-derivative. Thanks for confirming that I´d made the mistake!

Homework Statement Find the primitive function s(t) for v(t)=3(sin(3t) + cos(3t)) for which s(0)=0 The Attempt at a Solution v(t) =3(sin(3t) + cos(3t)) = 3sin3t +3cos3t s(t) =cos3t -sin3t + C 0 = cos3(0) - sin3(0) + C 0= 1 + C C=-1 such that my primitive function is cos3t -...

Ok, thanks for explaining!

Perfect. Now I get it! thanks a lot!

Homework Statement According to my math book, I solved the following trig equation correctly: 1) cos3x=0,500= 3x = 60° + n360° x=20+n120° 2)I also solved this problem correctly: 4sin^2x -3sin^x= 0 sinx(4sinx-3)=0 x=n*360° or 4sinx=3 sinx=3/4 x= ca. 49° x=49° + n360° or 131+ n360°. Now I´m...

Ok. I´ll do my best. Thanks once again!

Perfect! Now I got it. Thanks a lot! you´ve been a massive help. Do you have any general tips on how to solve such problems?

There are two options: 1) 1 + cos^2x -sin^2x = 1+cos^2x - (1-cos^2x)=2cos^2x 2) 1+(1-sin^2x)-sin^2x= 1+1 - sin^2x -sin^2x = 2-2sin^2x = 2(1-sin^2x) ?

1 + cos^2x - sin^2x ?

2sin2x(cos2x + 1)?

Somehow it keeps on getting more and more complicated. Do you have any idea on how I could keep it "simple"? sin4x + 2sin2x = 8sinxcos^3x on the left hand side: 2sin2xcos2x + 2sin2x = 2*2sinxcosx(cos^2x - sin^2x) + 2*2sinxcosx = 4sinxcos^3x - 2sin^3xcosx + 4sinxcosx It really doesn´t feel right...

Ah! I see. Thanks! sin2*2x= 2sin2xcos2x. I´ll carry on now and see if I get anywhere.

2sinAcosA? Or is this some sort of a trick question?

Ok, did you derive that from sin2x = 2sinxcosx? In that case, I don´t understand why sin4x = 2sin2xcos2x and not 4sin2xcos2x (i.e twice as much as sin2x = 2sinxcosx?)

Homework Statement show that sin4x + 2sin2x = 8sinxcos^3x Homework Equations sin2x =2sinxcosx The Attempt at a Solution I started out by letting sin4x = sin(2x*2) so that I could plugg in sin2x = 2sinxcosx in the equation. sin(2x*2) +2sin2x = sin2*sin2x +2sin2x = sin2 *...