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Hi my name is Matt I am doing research right now on resonant frequencies and a little on destructive interference I am interested in finding some experiments that could help me learn I've found that the cosine wave is 90 degrees out of phase from a sine wave, so is a negative sine wave 180 degrees from a regular sine or do you have to use a different function. What if I want a wave 45 or 30 degrees out of phase? Most of this I am going to try to directly apply to the electronics field. Also if anyone knows a schematic or plans for a inexpensive home-made sine wave generator I would be glad to hear from you. Any response would be welcome matthew e greer

Yes, a negative sine wave is 180 degrees from a regular sine. Actually, you can use a sine (or cosine) to describe all the different phase angles. If the frequency is w then the sine wave is described by sin(wt) If you just add whatever angle you want to the wt angle then you have what you want: sin(wt + p) is the expression for a sine wave shifted by an angle p. You can check for yourself that sin(wt + 90) = cos(wt), and sin(wt + 180) = -sin(wt) (that is assuming you are calculated the angles in degrees). Oh the "t" in the above expressions is supposed to mean time.

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