101. consider two wave functions that differ only by a phase shift, y1(x, t)=acos(kx−ωt)y1(x, t)=acos(kx−ωt) and y2(x, t)=acos(kx−ωt+ϕ).y2(x, t)=acos(kx−ωt+ϕ). use the trigonometric identities cosu+cosv=2cos(u−v2)cos(u+v2)cosu+c osv=2cos(u−v2)cos(u+v2) and cos(−θ)=cos(θ)cos(−θ)=cos(θ) to find a wave equation for the wave resulting from the superposition of the two waves. does the resulting wave function come as a surprise to you?