%display latex

var('t, s, alpha, delta, A, L, theta, omega')

$$\newcommand{\Bold}[1]{\mathbf{#1}}\left(t, s, \alpha, \delta, A, L, \theta, \omega\right)$$

k = function('k')(t)

de = diff(k, t) == s * k ^ alpha - k * (delta + A + L + 2 * theta * sin(2 * pi * t / omega))
show(de)

$$\newcommand{\Bold}[1]{\mathbf{#1}}\frac{\partial}{\partial t}k\left(t\right) = s k\left(t\right)^{\alpha} - {\left(2 \, \theta \sin\left(\frac{2 \, \pi t}{\omega}\right) + A + L + \delta\right)} k\left(t\right)$$

solution = desolve(de, k, ivar=t, show_method=True)
show(solution)

$$\newcommand{\Bold}[1]{\mathbf{#1}}\left[{\left(-{\left(\alpha - 1\right)} s \int e^{\left(-{\left(A t + L t + \delta t - \frac{\omega \theta \cos\left(\frac{2 \, \pi t}{\omega}\right)}{\pi}\right)} {\left(\alpha - 1\right)}\right)}\,{d t} + C\right)}^{-\frac{1}{\alpha - 1}} e^{\left(-A t - L t - \delta t + \frac{\omega \theta \cos\left(\frac{2 \, \pi t}{\omega}\right)}{\pi}\right)}, \verb|bernoulli|\right]$$