
Yohannes B. answered 11/16/21
I am happy to provide quality tutoring service in math and physics
Start from the general equation. f(t) = A*sin(ωt - Θ) = A*sin(2πft - Θ)
where A = Amplitude , ω = 2*π*f*t = angular frequency[rad/sec]
f = frequency[cycle/sec] , t = time[s] , Θ = angle[rad]
given A = 1/3 , T = π /4 => f = 1/T = 4/π , Θ = -π/3
hence f(t) = 1/3sin((2*π*4/π)t - (-π/3))
after simplification
f(t) = (1/3)sin(8t+π/3)