Question:

When two progressive waves y1=4sin(2x-6t) and y2=3sin(2x-6t-π/2) are superimposed, the amplitude of the resultant wave is?

Resultant amplitude=√(A₁² + A₂² + 2A₁A₂cosθ)
phase difference=θ=π/2
=√4²+3²=5