Two sinusoidal waves of the same period

[kukulalalu89]

Two sinusoidal waves, identical except for phase, travel in the same direction along a string and interfere to produce a resultant wave given by

y(x,t)=(2.5 mm)sin(26.0x -4.0 s-1 * t+0.400 rad),

with x in meters and t in seconds.

1.) What is the wavelength of the two waves (m)? [I already solved this]

2.) What is the phase difference between them (radians, so enter no unit)?

3.) What is their amplitude (mm)?


Please HELP on #2 and #3!!!

[turin]

Show your work.

[kukulalalu89]

for number 1,

y =Asin(kx-wt)

k = 2∏/λ

k = 26

so λ = 2∏/26 = wavelength = 0.242 m.

But I'm having problems with 2 and 3.

[turin]

Show work for #2 and #3.