The diagram below shows a sinusoidal curve. The equation of the curve will be

Let T be the time period; then T2=5π64−π64=4π64T=π8s ∴ω=2πT=2π(π/8)=16rad/sAlso, A = 10 cm (from the graph)The equation of the sinusoidal wave can be written as y=10sin⁡(16t+ϕ), where ϕ is the initial phase.From the graph, corresponding to the crest = 10 cm; when t=3π/64.    10cm=10sin⁡163π64+ϕcm    sin⁡3π4+ϕ=1  or  3π4+ϕ=π2⇒ϕ=−π4∴     y=10sin⁡16t−π4