the phase of a particle at t is 70 degree and other particle at 790 degree what is the wavelength if the distance between two particle is 1 metre

Wavelength is the length traversed by the wave when it moves by an angle of 2*π that is 360 degrees . Here the two particles are (790-70) =720 degrees apart that is equal to 4*π or 2*360. So the wavelength is half of the length i.e. 0.5metre .