Given a wave that begins at a point source that travels outward spherically, i know that for a 1D wave (from the solution of the wave equation) the amplitude at a given radius and time from the point source is: 1) A(r,t) = (1/r)*A(0)*sin(kr-wt) (or is this cosine because we take the real part of the full solution which is of the form e^i*theta = cos(theta) + i sin(theta)??). Many sites on the net use the sine form. 2) I wanted to know what the pressure at a particular radius and time was. I know it resembles the equation for A(r,t) because they are proportional. Again is it a sine or cosine form of solution??? 3) Even though this is a travelling wave, does the wavelength (between peak amplitudes/pressures for example) remain the same as it travels??