- #1
iRaid
- 559
- 8
I have a homework problem that I need to use the steady periodic oscillation to solve, so instead of having help on the problem I'd rather just understand how they did it then apply it to my homework (I think that's alright?)
I'm kind of wondering where my book gets this from: $$x_{sp}(t)=5cos4t+4sin4t=\sqrt{41}\left( \frac{5}{\sqrt{41}}cos4t+\frac{4}{\sqrt{41}}sin4t \right)=\sqrt{41}cos(4t-\alpha)$$
Honestly, I have no idea where they even get the square root of 41 either..
I feel like it's some trig substitution, identity, etc. that I'm forgetting, but I can't figure it outAny help is appreciated.
I'm kind of wondering where my book gets this from: $$x_{sp}(t)=5cos4t+4sin4t=\sqrt{41}\left( \frac{5}{\sqrt{41}}cos4t+\frac{4}{\sqrt{41}}sin4t \right)=\sqrt{41}cos(4t-\alpha)$$
Honestly, I have no idea where they even get the square root of 41 either..
I feel like it's some trig substitution, identity, etc. that I'm forgetting, but I can't figure it outAny help is appreciated.
Last edited: