The displacement of a particle executing simple harmonic motion is given by y = A0+Asin ωt+B cos ωt. Then the amplitude of its oscillation is given by

y = A0+(A sin ωt + B cos ωt)    = A0+Asin ωt+B sin(ωt+π2)Hence 2 SHMs are superimposed with phase difference of π2Amplitude a = A2+B2+2ABcos∆∅As, ∆∅ = π2 Hence a = A2+B2y = A0+A2+B2 sin(ωt6ϕ)A0 is mean position, and A2+B2 is amplitude