Find the derivative of the function f(t) =7tsin(πt) .
a) fᵗ = 7πtcos(πt) + 7sin(πt)
b) fᵗ = 7πtcos(πt) - 7sin(πt)
c) fᵗ = 7πtcos(πt)
d) fᵗ = -7πtcos(πt) - 7sin(πt)