Let me start by saying this is just a problem posed to me. I had this prof before so some people thought I might could see what he was thinking. OK here is the problem two in phase sources of waves are separated by a distance of 4.00m these sources produce identical waves that have a wave length of 5.00 m. on the line between them there are two places at which the same type of interference occurs. a: is it constructive or destructive interference and b: where are the places located answer: destructive and at .75m and 3.25m the problem can be solved simply using a destructive interference equation where L1 and L2 are distance traveled by wave. L2-L1 = (m+1/2) lamba L2 = 4-x L1 = x That's not the problem , the professor claims this can easily be solved using just two wave equations. Asin((2pi/wavelength)x) = Asin((2pi/wavelength)(x+1) The claim is that if you graph this equation in a TI or Excel you get the solutions at the 0 x intercept However algebraic solutions to this doesn't work. So my first question is can this problem be solved just using wave equations. I figure it can if you know the phase difference. My second is why would this work graphically and not algebraically. What a great way to spend a Friday night!