Two waves are represented by pressure changes
P1(x, t) = P0 cos(kx - ωt + π/4),
P2(x, t) = P0/2 sin (kx - ωt + π/4),
with k = 2π/λ. What is the total pressure at (i) x = λ and t = 0 (ii)
x = λ and t = 2π/3ω. Also calculate the amplitude of total pressure.